diff --git a/PIL/WebPImagePlugin.py b/PIL/WebPImagePlugin.py
index b93e0d3e7..36579dddd 100644
--- a/PIL/WebPImagePlugin.py
+++ b/PIL/WebPImagePlugin.py
@@ -3,6 +3,11 @@ from io import BytesIO
 
 
 _VALID_WEBP_MODES = {
+    "RGBX": True,
+    "RGBA": True,
+    }
+
+_VALID_WEBP_LEGACY_MODES = {
     "RGB": True,
     "RGBA": True,
     }
@@ -28,32 +33,263 @@ class WebPImageFile(ImageFile.ImageFile):
     format_description = "WebP image"
 
     def _open(self):
-        data, width, height, self.mode, icc_profile, exif = \
-            _webp.WebPDecode(self.fp.read())
+        if not _webp.HAVE_WEBPANIM:
+            # Legacy mode
+            data, width, height, self.mode, icc_profile, exif = \
+                _webp.WebPDecode(self.fp.read())
+            if icc_profile:
+                self.info["icc_profile"] = icc_profile
+            if exif:
+                self.info["exif"] = exif
+            self.size = width, height
+            self.fp = BytesIO(data)
+            self.tile = [("raw", (0, 0) + self.size, 0, self.mode)]
+            self._n_frames = 1
+            return
 
+        # Use the newer AnimDecoder API to parse the (possibly) animated file,
+        # and access muxed chunks like ICC/EXIF/XMP.
+        self._decoder = _webp.WebPAnimDecoder(self.fp.read())
+
+        # Get info from decoder
+        width, height, loop_count, bgcolor, frame_count, mode = \
+            self._decoder.get_info()
+        self.size = width, height
+        self.info["loop"] = loop_count
+        bg_a, bg_r, bg_g, bg_b = \
+            (bgcolor >> 24) & 0xFF, \
+            (bgcolor >> 16) & 0xFF, \
+            (bgcolor >> 8) & 0xFF, \
+            bgcolor & 0xFF
+        self.info["background"] = (bg_r, bg_g, bg_b, bg_a)
+        self._n_frames = frame_count
+        self.mode = mode
+        self.tile = []
+
+        # Attempt to read ICC / EXIF / XMP chunks from file
+        icc_profile = self._decoder.get_chunk("ICCP")
+        exif = self._decoder.get_chunk("EXIF")
+        xmp = self._decoder.get_chunk("XMP ")
         if icc_profile:
             self.info["icc_profile"] = icc_profile
         if exif:
             self.info["exif"] = exif
+        if xmp:
+            self.info["xmp"] = xmp
 
-        self.size = width, height
-        self.fp = BytesIO(data)
-        self.tile = [("raw", (0, 0) + self.size, 0, self.mode)]
+        # Initialize seek state
+        self._reset(reset=False)
+        self.seek(0)
 
     def _getexif(self):
         from .JpegImagePlugin import _getexif
         return _getexif(self)
 
+    @property
+    def n_frames(self):
+        return self._n_frames
+
+    @property
+    def is_animated(self):
+        return self._n_frames > 1
+
+    def seek(self, frame):
+        if not _webp.HAVE_WEBPANIM:
+            return super(WebPImageFile, self).seek(frame)
+
+        # Perform some simple checks first
+        if frame >= self._n_frames:
+            raise EOFError("attempted to seek beyond end of sequence")
+        if frame < 0:
+            raise EOFError("negative frame index is not valid")
+
+        # Set logical frame to requested position
+        self.__logical_frame = frame
+
+    def _reset(self, reset=True):
+        if reset:
+            self._decoder.reset()
+        self.__physical_frame = 0
+        self.__loaded = -1
+        self.__timestamp = 0
+
+    def _get_next(self):
+        # Get next frame
+        ret = self._decoder.get_next()
+        self.__physical_frame += 1
+
+        # Check if an error occurred
+        if ret is None:
+            self._reset()   # Reset just to be safe
+            self.seek(0)
+            raise EOFError("failed to decode next frame in WebP file")
+
+        # Compute duration
+        data, timestamp = ret
+        duration = timestamp - self.__timestamp
+        self.__timestamp = timestamp
+
+        # libwebp gives frame end, adjust to start of frame
+        timestamp -= duration
+        return data, timestamp, duration
+
+    def _seek(self, frame):
+        if self.__physical_frame == frame:
+            return              # Nothing to do
+        if frame < self.__physical_frame:
+            self._reset()       # Rewind to beginning
+        while self.__physical_frame < frame:
+            self._get_next()    # Advance to the requested frame
+
+    def load(self):
+        if _webp.HAVE_WEBPANIM:
+            if self.__loaded != self.__logical_frame:
+                self._seek(self.__logical_frame)
+
+                # We need to load the image data for this frame
+                data, timestamp, duration = self._get_next()
+                self.info["timestamp"] = timestamp
+                self.info["duration"] = duration
+                self.__loaded = self.__logical_frame
+
+                # Set tile
+                self.fp = BytesIO(data)
+                self.tile = [("raw", (0, 0) + self.size, 0, self.mode)]
+
+        return super(WebPImageFile, self).load()
+
+    def tell(self):
+        if not _webp.HAVE_WEBPANIM:
+            return super(WebPImageFile, self).tell()
+
+        return self.__logical_frame
+
+
+def _save_all(im, fp, filename):
+    encoderinfo = im.encoderinfo.copy()
+    append_images = encoderinfo.get("append_images", [])
+
+    # If total frame count is 1, then save using the legacy API, which
+    # will preserve non-alpha modes
+    total = 0
+    for ims in [im]+append_images:
+        total += 1 if not hasattr(ims, "n_frames") else ims.n_frames
+    if total == 1:
+        _save(im, fp, filename)
+        return
+
+    background = encoderinfo.get("background", (0, 0, 0, 0))
+    duration = im.encoderinfo.get("duration", 0)
+    loop = im.encoderinfo.get("loop", 0)
+    minimize_size = im.encoderinfo.get("minimize_size", False)
+    kmin = im.encoderinfo.get("kmin", None)
+    kmax = im.encoderinfo.get("kmax", None)
+    allow_mixed = im.encoderinfo.get("allow_mixed", False)
+    verbose = False
+    lossless = im.encoderinfo.get("lossless", False)
+    quality = im.encoderinfo.get("quality", 80)
+    method = im.encoderinfo.get("method", 0)
+    icc_profile = im.encoderinfo.get("icc_profile", "")
+    exif = im.encoderinfo.get("exif", "")
+    xmp = im.encoderinfo.get("xmp", "")
+    if allow_mixed:
+        lossless = False
+
+    # Sensible keyframe defaults are from gif2webp.c script
+    if kmin is None:
+        kmin = 9 if lossless else 3
+    if kmax is None:
+        kmax = 17 if lossless else 5
+
+    # Validate background color
+    if (not isinstance(background, (list, tuple)) or len(background) != 4 or
+            not all(v >= 0 and v < 256 for v in background)):
+        raise IOError("Background color is not an RGBA tuple clamped "
+                      "to (0-255): %s" % str(background))
+
+    # Convert to packed uint
+    bg_r, bg_g, bg_b, bg_a = background
+    background = (bg_a << 24) | (bg_r << 16) | (bg_g << 8) | (bg_b << 0)
+
+    # Setup the WebP animation encoder
+    enc = _webp.WebPAnimEncoder(
+        im.size[0], im.size[1],
+        background,
+        loop,
+        minimize_size,
+        kmin, kmax,
+        allow_mixed,
+        verbose
+    )
+
+    # Add each frame
+    frame_idx = 0
+    timestamp = 0
+    cur_idx = im.tell()
+    try:
+        for ims in [im]+append_images:
+            # Get # of frames in this image
+            if not hasattr(ims, "n_frames"):
+                nfr = 1
+            else:
+                nfr = ims.n_frames
+
+            for idx in range(nfr):
+                ims.seek(idx)
+                ims.load()
+
+                # Make sure image mode is supported
+                frame = ims
+                if ims.mode not in _VALID_WEBP_MODES:
+                    alpha = ims.mode == 'P' and 'A' in ims.im.getpalettemode()
+                    frame = ims.convert('RGBA' if alpha else 'RGBX')
+
+                # Append the frame to the animation encoder
+                enc.add(
+                    frame.tobytes(),
+                    timestamp,
+                    frame.size[0], frame.size[1],
+                    frame.mode,
+                    lossless,
+                    quality,
+                    method
+                )
+
+                # Update timestamp and frame index
+                if isinstance(duration, (list, tuple)):
+                    timestamp += duration[frame_idx]
+                else:
+                    timestamp += duration
+                frame_idx += 1
+
+    finally:
+        im.seek(cur_idx)
+
+    # Force encoder to flush frames
+    enc.add(
+        None,
+        timestamp,
+        0, 0, "", lossless, quality, 0
+    )
+
+    # Get the final output from the encoder
+    data = enc.assemble(icc_profile, exif, xmp)
+    if data is None:
+        raise IOError("cannot write file as WebP (encoder returned None)")
+
+    fp.write(data)
+
 
 def _save(im, fp, filename):
-    image_mode = im.mode
-    if im.mode not in _VALID_WEBP_MODES:
-        raise IOError("cannot write mode %s as WEBP" % image_mode)
-
     lossless = im.encoderinfo.get("lossless", False)
     quality = im.encoderinfo.get("quality", 80)
     icc_profile = im.encoderinfo.get("icc_profile", "")
     exif = im.encoderinfo.get("exif", "")
+    xmp = im.encoderinfo.get("xmp", "")
+
+    if im.mode not in _VALID_WEBP_LEGACY_MODES:
+        alpha = im.mode == 'P' and 'A' in im.im.getpalettemode()
+        im = im.convert('RGBA' if alpha else 'RGB')
 
     data = _webp.WebPEncode(
         im.tobytes(),
@@ -63,16 +299,18 @@ def _save(im, fp, filename):
         float(quality),
         im.mode,
         icc_profile,
-        exif
+        exif,
+        xmp
     )
     if data is None:
-        raise IOError("cannot write file as WEBP (encoder returned None)")
+        raise IOError("cannot write file as WebP (encoder returned None)")
 
     fp.write(data)
 
 
 Image.register_open(WebPImageFile.format, WebPImageFile, _accept)
 Image.register_save(WebPImageFile.format, _save)
-
+if _webp.HAVE_WEBPANIM:
+    Image.register_save_all(WebPImageFile.format, _save_all)
 Image.register_extension(WebPImageFile.format, ".webp")
 Image.register_mime(WebPImageFile.format, "image/webp")
diff --git a/PIL/features.py b/PIL/features.py
index 60f4c10ca..9cbd523c9 100644
--- a/PIL/features.py
+++ b/PIL/features.py
@@ -43,6 +43,7 @@ def get_supported_codecs():
     return [f for f in codecs if check_codec(f)]
 
 features = {
+    "webp_anim": ("PIL._webp", 'HAVE_WEBPANIM'),
     "webp_mux": ("PIL._webp", 'HAVE_WEBPMUX'),
     "transp_webp": ("PIL._webp", "HAVE_TRANSPARENCY"),
     "raqm": ("PIL._imagingft", "HAVE_RAQM")
@@ -53,7 +54,7 @@ def check_feature(feature):
         raise ValueError("Unknown feature %s" % feature)
 
     module, flag = features[feature]
-    
+
     try:
         imported_module = __import__(module, fromlist=['PIL'])
         return getattr(imported_module, flag)
@@ -75,4 +76,4 @@ def get_supported():
     ret.extend(get_supported_features())
     ret.extend(get_supported_codecs())
     return ret
-        
+
diff --git a/Tests/images/anim_frame1.webp b/Tests/images/anim_frame1.webp
new file mode 100644
index 000000000..74e1592bd
Binary files /dev/null and b/Tests/images/anim_frame1.webp differ
diff --git a/Tests/images/anim_frame2.webp b/Tests/images/anim_frame2.webp
new file mode 100644
index 000000000..88c240af3
Binary files /dev/null and b/Tests/images/anim_frame2.webp differ
diff --git a/Tests/images/iss634.webp b/Tests/images/iss634.webp
new file mode 100644
index 000000000..5181da736
Binary files /dev/null and b/Tests/images/iss634.webp differ
diff --git a/Tests/images/transparent.gif b/Tests/images/transparent.gif
new file mode 100644
index 000000000..911e4ee34
Binary files /dev/null and b/Tests/images/transparent.gif differ
diff --git a/Tests/test_features.py b/Tests/test_features.py
index cdabcad5e..54d668d2f 100644
--- a/Tests/test_features.py
+++ b/Tests/test_features.py
@@ -35,6 +35,11 @@ class TestFeatures(PillowTestCase):
         self.assertEqual(features.check('webp_mux'),
                          _webp.HAVE_WEBPMUX)
 
+    @unittest.skipUnless(HAVE_WEBP, True)
+    def check_webp_anim(self):
+        self.assertEqual(features.check('webp_anim'),
+                         _webp.HAVE_WEBPANIM)
+
     def test_check_modules(self):
         for feature in features.modules:
             self.assertIn(features.check_module(feature), [True, False])
diff --git a/Tests/test_file_webp.py b/Tests/test_file_webp.py
index 6c16882fd..06e274d0a 100644
--- a/Tests/test_file_webp.py
+++ b/Tests/test_file_webp.py
@@ -4,29 +4,35 @@ from PIL import Image
 
 try:
     from PIL import _webp
+    HAVE_WEBP = True
 except ImportError:
-    # Skip in setUp()
-    pass
+    HAVE_WEBP = False
 
 
 class TestFileWebp(PillowTestCase):
 
     def setUp(self):
-        try:
-            from PIL import _webp
-        except ImportError:
+        if not HAVE_WEBP:
             self.skipTest('WebP support not installed')
+            return
+
+        # WebPAnimDecoder only returns RGBA or RGBX, never RGB
+        self.rgb_mode = "RGBX" if _webp.HAVE_WEBPANIM else "RGB"
 
     def test_version(self):
         _webp.WebPDecoderVersion()
         _webp.WebPDecoderBuggyAlpha()
 
     def test_read_rgb(self):
+        """
+        Can we read a RGB mode WebP file without error?
+        Does it have the bits we expect?
+        """
 
         file_path = "Tests/images/hopper.webp"
         image = Image.open(file_path)
 
-        self.assertEqual(image.mode, "RGB")
+        self.assertEqual(image.mode, self.rgb_mode)
         self.assertEqual(image.size, (128, 128))
         self.assertEqual(image.format, "WEBP")
         image.load()
@@ -35,6 +41,7 @@ class TestFileWebp(PillowTestCase):
         # generated with:
         # dwebp -ppm ../../Tests/images/hopper.webp -o hopper_webp_bits.ppm
         target = Image.open('Tests/images/hopper_webp_bits.ppm')
+        target = target.convert(self.rgb_mode)
         self.assert_image_similar(image, target, 20.0)
 
     def test_write_rgb(self):
@@ -45,12 +52,10 @@ class TestFileWebp(PillowTestCase):
 
         temp_file = self.tempfile("temp.webp")
 
-        hopper("RGB").save(temp_file)
-
+        hopper(self.rgb_mode).save(temp_file)
         image = Image.open(temp_file)
-        image.load()
 
-        self.assertEqual(image.mode, "RGB")
+        self.assertEqual(image.mode, self.rgb_mode)
         self.assertEqual(image.size, (128, 128))
         self.assertEqual(image.format, "WEBP")
         image.load()
@@ -69,20 +74,67 @@ class TestFileWebp(PillowTestCase):
         # then we're going to accept that it's a reasonable lossy version of
         # the image. The old lena images for WebP are showing ~16 on
         # Ubuntu, the jpegs are showing ~18.
-        target = hopper("RGB")
-        self.assert_image_similar(image, target, 12)
+        target = hopper(self.rgb_mode)
+        self.assert_image_similar(image, target, 12.0)
+
+    def test_write_unsupported_mode_L(self):
+        """
+        Saving a black-and-white file to WebP format should work, and be
+        similar to the original file.
+        """
 
-    def test_write_unsupported_mode(self):
         temp_file = self.tempfile("temp.webp")
+        hopper("L").save(temp_file)
+        image = Image.open(temp_file)
 
-        im = hopper("L")
-        self.assertRaises(IOError, im.save, temp_file)
+        self.assertEqual(image.mode, self.rgb_mode)
+        self.assertEqual(image.size, (128, 128))
+        self.assertEqual(image.format, "WEBP")
+
+        image.load()
+        image.getdata()
+        target = hopper("L").convert(self.rgb_mode)
+
+        self.assert_image_similar(image, target, 10.0)
+
+    def test_write_unsupported_mode_P(self):
+        """
+        Saving a palette-based file to WebP format should work, and be
+        similar to the original file.
+        """
+
+        temp_file = self.tempfile("temp.webp")
+        hopper("P").save(temp_file)
+        image = Image.open(temp_file)
+
+        self.assertEqual(image.mode, self.rgb_mode)
+        self.assertEqual(image.size, (128, 128))
+        self.assertEqual(image.format, "WEBP")
+
+        image.load()
+        image.getdata()
+        target = hopper("P").convert(self.rgb_mode)
+
+        self.assert_image_similar(image, target, 50.0)
 
     def test_WebPEncode_with_invalid_args(self):
+        """
+        Calling encoder functions with no arguments should result in an error.
+        """
+
+        if _webp.HAVE_WEBPANIM:
+            self.assertRaises(TypeError, _webp.WebPAnimEncoder)
         self.assertRaises(TypeError, _webp.WebPEncode)
 
     def test_WebPDecode_with_invalid_args(self):
+        """
+        Calling decoder functions with no arguments should result in an error.
+        """
+
+        if _webp.HAVE_WEBPANIM:
+            self.assertRaises(TypeError, _webp.WebPAnimDecoder)
         self.assertRaises(TypeError, _webp.WebPDecode)
 
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Tests/test_file_webp_alpha.py b/Tests/test_file_webp_alpha.py
index 70a4d7354..ef9d74f3a 100644
--- a/Tests/test_file_webp_alpha.py
+++ b/Tests/test_file_webp_alpha.py
@@ -22,6 +22,11 @@ class TestFileWebpAlpha(PillowTestCase):
                           "not testing transparency")
 
     def test_read_rgba(self):
+        """
+        Can we read an RGBA mode file without error?
+        Does it have the bits we expect?
+        """
+
         # Generated with `cwebp transparent.png -o transparent.webp`
         file_path = "Tests/images/transparent.webp"
         image = Image.open(file_path)
@@ -38,6 +43,11 @@ class TestFileWebpAlpha(PillowTestCase):
         self.assert_image_similar(image, target, 20.0)
 
     def test_write_lossless_rgb(self):
+        """
+        Can we write an RGBA mode file with lossless compression without
+        error? Does it have the bits we expect?
+        """
+
         temp_file = self.tempfile("temp.webp")
         # temp_file = "temp.webp"
 
@@ -90,6 +100,27 @@ class TestFileWebpAlpha(PillowTestCase):
         else:
             self.assert_image_similar(image, pil_image, 1.0)
 
+    def test_write_unsupported_mode_PA(self):
+        """
+        Saving a palette-based file with transparency to WebP format
+        should work, and be similar to the original file.
+        """
+
+        temp_file = self.tempfile("temp.webp")
+        file_path = "Tests/images/transparent.gif"
+        Image.open(file_path).save(temp_file)
+        image = Image.open(temp_file)
+
+        self.assertEqual(image.mode, "RGBA")
+        self.assertEqual(image.size, (200, 150))
+        self.assertEqual(image.format, "WEBP")
+
+        image.load()
+        image.getdata()
+        target = Image.open(file_path).convert("RGBA")
+
+        self.assert_image_similar(image, target, 10.0)
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Tests/test_file_webp_animated.py b/Tests/test_file_webp_animated.py
new file mode 100644
index 000000000..ba5d4b3af
--- /dev/null
+++ b/Tests/test_file_webp_animated.py
@@ -0,0 +1,145 @@
+from helper import unittest, PillowTestCase
+
+from PIL import Image
+
+try:
+    from PIL import _webp
+    HAVE_WEBP = True
+except ImportError:
+    HAVE_WEBP = False
+
+
+class TestFileWebpAnimation(PillowTestCase):
+
+    def setUp(self):
+        if not HAVE_WEBP:
+            self.skipTest('WebP support not installed')
+            return
+
+        if not _webp.HAVE_WEBPANIM:
+            self.skipTest("WebP library does not contain animation support, "
+                          "not testing animation")
+
+    def test_n_frames(self):
+        """
+        Ensure that WebP format sets n_frames and is_animated
+        attributes correctly.
+        """
+
+        im = Image.open("Tests/images/hopper.webp")
+        self.assertEqual(im.n_frames, 1)
+        self.assertFalse(im.is_animated)
+
+        im = Image.open("Tests/images/iss634.webp")
+        self.assertEqual(im.n_frames, 42)
+        self.assertTrue(im.is_animated)
+
+    def test_write_animation_L(self):
+        """
+        Convert an animated GIF to animated WebP, then compare the
+        frame count, and first and last frames to ensure they're
+        visually similar.
+        """
+
+        orig = Image.open("Tests/images/iss634.gif")
+        self.assertGreater(orig.n_frames, 1)
+
+        temp_file = self.tempfile("temp.webp")
+        orig.save(temp_file, save_all=True)
+        im = Image.open(temp_file)
+        self.assertEqual(im.n_frames, orig.n_frames)
+
+        # Compare first and last frames to the original animated GIF
+        orig.load()
+        im.load()
+        self.assert_image_similar(im, orig.convert("RGBA"), 25.0)
+        orig.seek(orig.n_frames-1)
+        im.seek(im.n_frames-1)
+        orig.load()
+        im.load()
+        self.assert_image_similar(im, orig.convert("RGBA"), 25.0)
+
+    def test_write_animation_RGB(self):
+        """
+        Write an animated WebP from RGB frames, and ensure the frames
+        are visually similar to the originals.
+        """
+
+        temp_file = self.tempfile("temp.webp")
+        temp_file2 = self.tempfile("temp.png")
+        frame1 = Image.open('Tests/images/anim_frame1.webp')
+        frame2 = Image.open('Tests/images/anim_frame2.webp')
+        frame1.save(temp_file,
+            save_all=True, append_images=[frame2], lossless=True)
+
+        im = Image.open(temp_file)
+        self.assertEqual(im.n_frames, 2)
+
+        # Compare first frame to original
+        im.load()
+        im.save(temp_file2)
+        self.assert_image_equal(im, frame1.convert("RGBA"))
+
+        # Compare second frame to original
+        im.seek(1)
+        im.load()
+        self.assert_image_equal(im, frame2.convert("RGBA"))
+
+    def test_timestamp_and_duration(self):
+        """
+        Try passing a list of durations, and make sure the encoded
+        timestamps and durations are correct.
+        """
+
+        durations = [0, 10, 20, 30, 40]
+        temp_file = self.tempfile("temp.webp")
+        frame1 = Image.open('Tests/images/anim_frame1.webp')
+        frame2 = Image.open('Tests/images/anim_frame2.webp')
+        frame1.save(temp_file, save_all=True,
+                    append_images=[frame2, frame1, frame2, frame1],
+                    duration=durations)
+
+        im = Image.open(temp_file)
+        self.assertEqual(im.n_frames, 5)
+        self.assertTrue(im.is_animated)
+
+        # Check that timestamps and durations match original values specified
+        ts = 0
+        for frame in range(im.n_frames):
+            im.seek(frame)
+            im.load()
+            self.assertEqual(im.info["duration"], durations[frame])
+            self.assertEqual(im.info["timestamp"], ts)
+            ts += durations[frame]
+
+    def test_seeking(self):
+        """
+        Create an animated WebP file, and then try seeking through
+        frames in reverse-order, verifying the timestamps and durations
+        are correct.
+        """
+
+        dur = 33
+        temp_file = self.tempfile("temp.webp")
+        frame1 = Image.open('Tests/images/anim_frame1.webp')
+        frame2 = Image.open('Tests/images/anim_frame2.webp')
+        frame1.save(temp_file, save_all=True,
+                    append_images=[frame2, frame1, frame2, frame1],
+                    duration=dur)
+
+        im = Image.open(temp_file)
+        self.assertEqual(im.n_frames, 5)
+        self.assertTrue(im.is_animated)
+
+        # Traverse frames in reverse, checking timestamps and durations
+        ts = dur * (im.n_frames-1)
+        for frame in reversed(range(im.n_frames)):
+            im.seek(frame)
+            im.load()
+            self.assertEqual(im.info["duration"], dur)
+            self.assertEqual(im.info["timestamp"], ts)
+            ts -= dur
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/Tests/test_file_webp_lossless.py b/Tests/test_file_webp_lossless.py
index f653eb8b4..10354c55f 100644
--- a/Tests/test_file_webp_lossless.py
+++ b/Tests/test_file_webp_lossless.py
@@ -4,37 +4,39 @@ from PIL import Image
 
 try:
     from PIL import _webp
+    HAVE_WEBP = True
 except ImportError:
-    pass
-    # Skip in setUp()
+    HAVE_WEBP = False
 
 
 class TestFileWebpLossless(PillowTestCase):
 
     def setUp(self):
-        try:
-            from PIL import _webp
-        except:
+        if not HAVE_WEBP:
             self.skipTest('WebP support not installed')
+            return
 
         if (_webp.WebPDecoderVersion() < 0x0200):
             self.skipTest('lossless not included')
 
+        # WebPAnimDecoder only returns RGBA or RGBX, never RGB
+        self.rgb_mode = "RGBX" if _webp.HAVE_WEBPANIM else "RGB"
+
     def test_write_lossless_rgb(self):
         temp_file = self.tempfile("temp.webp")
 
-        hopper("RGB").save(temp_file, lossless=True)
+        hopper(self.rgb_mode).save(temp_file, lossless=True)
 
         image = Image.open(temp_file)
         image.load()
 
-        self.assertEqual(image.mode, "RGB")
+        self.assertEqual(image.mode, self.rgb_mode)
         self.assertEqual(image.size, (128, 128))
         self.assertEqual(image.format, "WEBP")
         image.load()
         image.getdata()
 
-        self.assert_image_equal(image, hopper("RGB"))
+        self.assert_image_equal(image, hopper(self.rgb_mode))
 
 
 if __name__ == '__main__':
diff --git a/Tests/test_file_webp_metadata.py b/Tests/test_file_webp_metadata.py
index 88e2b3b88..c04443f46 100644
--- a/Tests/test_file_webp_metadata.py
+++ b/Tests/test_file_webp_metadata.py
@@ -2,13 +2,17 @@ from helper import unittest, PillowTestCase
 
 from PIL import Image
 
+try:
+    from PIL import _webp
+    HAVE_WEBP = True
+except ImportError:
+    HAVE_WEBP = False
+
 
 class TestFileWebpMetadata(PillowTestCase):
 
     def setUp(self):
-        try:
-            from PIL import _webp
-        except ImportError:
+        if not HAVE_WEBP:
             self.skipTest('WebP support not installed')
             return
 
@@ -107,6 +111,29 @@ class TestFileWebpMetadata(PillowTestCase):
 
         self.assertFalse(webp_image._getexif())
 
+    def test_write_animated_metadata(self):
+        if not _webp.HAVE_WEBPANIM:
+            self.skipTest('WebP animation support not available')
+
+        iccp_data = '<iccp_data>'.encode('utf-8')
+        exif_data = '<exif_data>'.encode('utf-8')
+        xmp_data = '<xmp_data>'.encode('utf-8')
+
+        temp_file = self.tempfile("temp.webp")
+        frame1 = Image.open('Tests/images/anim_frame1.webp')
+        frame2 = Image.open('Tests/images/anim_frame2.webp')
+        frame1.save(temp_file, save_all=True,
+                    append_images=[frame2, frame1, frame2],
+                    icc_profile=iccp_data, exif=exif_data, xmp=xmp_data)
+
+        image = Image.open(temp_file)
+        self.assertIn('icc_profile', image.info)
+        self.assertIn('exif', image.info)
+        self.assertIn('xmp', image.info)
+        self.assertEqual(iccp_data, image.info.get('icc_profile', None))
+        self.assertEqual(exif_data, image.info.get('exif', None))
+        self.assertEqual(xmp_data, image.info.get('xmp', None))
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/_webp.c b/_webp.c
index 260f2182b..67a9e6b66 100644
--- a/_webp.c
+++ b/_webp.c
@@ -8,27 +8,551 @@
 
 #ifdef HAVE_WEBPMUX
 #include <webp/mux.h>
+#include <webp/demux.h>
+
+/*
+ * Check the versions from mux.h and demux.h, to ensure the WebPAnimEncoder and
+ * WebPAnimDecoder APIs are present (initial support was added in 0.5.0). The
+ * very early versions added had some significant differences, so we require
+ * later versions, before enabling animation support.
+ */
+#if WEBP_MUX_ABI_VERSION >= 0x0104 && WEBP_DEMUX_ABI_VERSION >= 0x0105
+#define HAVE_WEBPANIM
 #endif
 
+#endif
+
+/* -------------------------------------------------------------------- */
+/* WebP Muxer Error Handling                                            */
+/* -------------------------------------------------------------------- */
+
+#ifdef HAVE_WEBPMUX
+
+static const char* const kErrorMessages[-WEBP_MUX_NOT_ENOUGH_DATA + 1] = {
+    "WEBP_MUX_NOT_FOUND", "WEBP_MUX_INVALID_ARGUMENT", "WEBP_MUX_BAD_DATA",
+    "WEBP_MUX_MEMORY_ERROR", "WEBP_MUX_NOT_ENOUGH_DATA"
+};
+
+PyObject* HandleMuxError(WebPMuxError err, char* chunk) {
+    char message[100];
+    int message_len;
+    assert(err <= WEBP_MUX_NOT_FOUND && err >= WEBP_MUX_NOT_ENOUGH_DATA);
+
+    // Check for a memory error first
+    if (err == WEBP_MUX_MEMORY_ERROR) {
+        return PyErr_NoMemory();
+    }
+
+    // Create the error message
+    if (chunk == NULL) {
+        message_len = sprintf(message, "could not assemble chunks: %s", kErrorMessages[-err]);
+    } else {
+        message_len = sprintf(message, "could not set %.4s chunk: %s", chunk, kErrorMessages[-err]);
+    }
+    if (message_len < 0) {
+        PyErr_SetString(PyExc_RuntimeError, "failed to construct error message");
+        return NULL;
+    }
+
+    // Set the proper error type
+    switch (err) {
+        case WEBP_MUX_NOT_FOUND:
+        case WEBP_MUX_INVALID_ARGUMENT:
+            PyErr_SetString(PyExc_ValueError, message);
+            break;
+
+        case WEBP_MUX_BAD_DATA:
+        case WEBP_MUX_NOT_ENOUGH_DATA:
+            PyErr_SetString(PyExc_IOError, message);
+            break;
+
+        default:
+            PyErr_SetString(PyExc_RuntimeError, message);
+            break;
+    }
+    return NULL;
+}
+
+#endif
+
+/* -------------------------------------------------------------------- */
+/* WebP Animation Support                                               */
+/* -------------------------------------------------------------------- */
+
+#ifdef HAVE_WEBPANIM
+
+// Encoder type
+typedef struct {
+    PyObject_HEAD
+    WebPAnimEncoder* enc;
+    WebPPicture frame;
+} WebPAnimEncoderObject;
+
+static PyTypeObject WebPAnimEncoder_Type;
+
+// Decoder type
+typedef struct {
+    PyObject_HEAD
+    WebPAnimDecoder* dec;
+    WebPAnimInfo info;
+    WebPData data;
+    char* mode;
+} WebPAnimDecoderObject;
+
+static PyTypeObject WebPAnimDecoder_Type;
+
+// Encoder functions
+PyObject* _anim_encoder_new(PyObject* self, PyObject* args)
+{
+    int width, height;
+    uint32_t bgcolor;
+    int loop_count;
+    int minimize_size;
+    int kmin, kmax;
+    int allow_mixed;
+    int verbose;
+    WebPAnimEncoderOptions enc_options;
+    WebPAnimEncoderObject* encp = NULL;
+    WebPAnimEncoder* enc = NULL;
+
+    if (!PyArg_ParseTuple(args, "iiIiiiiii",
+        &width, &height, &bgcolor, &loop_count, &minimize_size,
+        &kmin, &kmax, &allow_mixed, &verbose)) {
+        return NULL;
+    }
+
+    // Setup and configure the encoder's options (these are animation-specific)
+    if (!WebPAnimEncoderOptionsInit(&enc_options)) {
+        PyErr_SetString(PyExc_RuntimeError, "failed to initialize encoder options");
+        return NULL;
+    }
+    enc_options.anim_params.bgcolor = bgcolor;
+    enc_options.anim_params.loop_count = loop_count;
+    enc_options.minimize_size = minimize_size;
+    enc_options.kmin = kmin;
+    enc_options.kmax = kmax;
+    enc_options.allow_mixed = allow_mixed;
+    enc_options.verbose = verbose;
+
+    // Validate canvas dimensions
+    if (width <= 0 || height <= 0) {
+        PyErr_SetString(PyExc_ValueError, "invalid canvas dimensions");
+        return NULL;
+    }
+
+    // Create a new animation encoder and picture frame
+    encp = PyObject_New(WebPAnimEncoderObject, &WebPAnimEncoder_Type);
+    if (encp) {
+        if (WebPPictureInit(&(encp->frame))) {
+            enc = WebPAnimEncoderNew(width, height, &enc_options);
+            if (enc) {
+                encp->enc = enc;
+                return (PyObject*) encp;
+            }
+            WebPPictureFree(&(encp->frame));
+        }
+        PyObject_Del(encp);
+    }
+    PyErr_SetString(PyExc_RuntimeError, "could not create encoder object");
+    return NULL;
+}
+
+PyObject* _anim_encoder_dealloc(PyObject* self)
+{
+    WebPAnimEncoderObject* encp = (WebPAnimEncoderObject*)self;
+    WebPPictureFree(&(encp->frame));
+    WebPAnimEncoderDelete(encp->enc);
+    Py_RETURN_NONE;
+}
+
+PyObject* _anim_encoder_add(PyObject* self, PyObject* args)
+{
+    uint8_t* rgb;
+    Py_ssize_t size;
+    int timestamp;
+    int width;
+    int height;
+    char* mode;
+    int lossless;
+    float quality_factor;
+    int method;
+    WebPConfig config;
+    WebPAnimEncoderObject* encp = (WebPAnimEncoderObject*)self;
+    WebPAnimEncoder* enc = encp->enc;
+    WebPPicture* frame = &(encp->frame);
+
+    if (!PyArg_ParseTuple(args, "z#iiisifi",
+        (char**)&rgb, &size, &timestamp, &width, &height, &mode,
+        &lossless, &quality_factor, &method)) {
+        return NULL;
+    }
+
+    // Check for NULL frame, which sets duration of final frame
+    if (!rgb) {
+        WebPAnimEncoderAdd(enc, NULL, timestamp, NULL);
+        Py_RETURN_NONE;
+    }
+
+    // Setup config for this frame
+    if (!WebPConfigInit(&config)) {
+        PyErr_SetString(PyExc_RuntimeError, "failed to initialize config!");
+        return NULL;
+    }
+    config.lossless = lossless;
+    config.quality = quality_factor;
+    config.method = method;
+
+    // Validate the config
+    if (!WebPValidateConfig(&config)) {
+        PyErr_SetString(PyExc_ValueError, "invalid configuration");
+        return NULL;
+    }
+
+    // Populate the frame with raw bytes passed to us
+    frame->width = width;
+    frame->height = height;
+    frame->use_argb = 1; // Don't convert RGB pixels to YUV
+    if (strcmp(mode, "RGBA")==0) {
+        WebPPictureImportRGBA(frame, rgb, 4 * width);
+    } else if (strcmp(mode, "RGBX")==0) {
+        WebPPictureImportRGBX(frame, rgb, 4 * width);
+    }
+
+    // Add the frame to the encoder
+    if (!WebPAnimEncoderAdd(enc, frame, timestamp, &config)) {
+        PyErr_SetString(PyExc_RuntimeError, WebPAnimEncoderGetError(enc));
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
+PyObject* _anim_encoder_assemble(PyObject* self, PyObject* args)
+{
+    uint8_t* icc_bytes;
+    uint8_t* exif_bytes;
+    uint8_t* xmp_bytes;
+    Py_ssize_t icc_size;
+    Py_ssize_t exif_size;
+    Py_ssize_t xmp_size;
+    WebPData webp_data;
+    WebPAnimEncoderObject* encp = (WebPAnimEncoderObject*)self;
+    WebPAnimEncoder* enc = encp->enc;
+    WebPMux* mux = NULL;
+    PyObject* ret = NULL;
+
+    if (!PyArg_ParseTuple(args, "s#s#s#",
+    &icc_bytes, &icc_size, &exif_bytes, &exif_size, &xmp_bytes, &xmp_size)) {
+        return NULL;
+    }
+
+    // Init the output buffer
+    WebPDataInit(&webp_data);
+
+    // Assemble everything into the output buffer
+    if (!WebPAnimEncoderAssemble(enc, &webp_data)) {
+        PyErr_SetString(PyExc_RuntimeError, WebPAnimEncoderGetError(enc));
+        return NULL;
+    }
+
+    // Re-mux to add metadata as needed
+    if (icc_size > 0 || exif_size > 0 || xmp_size > 0) {
+        WebPMuxError err = WEBP_MUX_OK;
+        int i_icc_size = (int)icc_size;
+        int i_exif_size = (int)exif_size;
+        int i_xmp_size = (int)xmp_size;
+        WebPData icc_profile = { icc_bytes, i_icc_size };
+        WebPData exif = { exif_bytes, i_exif_size };
+        WebPData xmp = { xmp_bytes, i_xmp_size };
+
+        mux = WebPMuxCreate(&webp_data, 1);
+        if (mux == NULL) {
+            PyErr_SetString(PyExc_RuntimeError, "could not re-mux to add metadata");
+            return NULL;
+        }
+        WebPDataClear(&webp_data);
+
+        // Add ICCP chunk
+        if (i_icc_size > 0) {
+            err = WebPMuxSetChunk(mux, "ICCP", &icc_profile, 1);
+            if (err != WEBP_MUX_OK) {
+                return HandleMuxError(err, "ICCP");
+            }
+        }
+
+        // Add EXIF chunk
+        if (i_exif_size > 0) {
+            err = WebPMuxSetChunk(mux, "EXIF", &exif, 1);
+            if (err != WEBP_MUX_OK) {
+                return HandleMuxError(err, "EXIF");
+            }
+        }
+
+        // Add XMP chunk
+        if (i_xmp_size > 0) {
+            err = WebPMuxSetChunk(mux, "XMP ", &xmp, 1);
+            if (err != WEBP_MUX_OK) {
+                return HandleMuxError(err, "XMP");
+            }
+        }
+
+        err = WebPMuxAssemble(mux, &webp_data);
+        if (err != WEBP_MUX_OK) {
+            return HandleMuxError(err, NULL);
+        }
+    }
+
+    // Convert to Python bytes
+    ret = PyBytes_FromStringAndSize((char*)webp_data.bytes, webp_data.size);
+    WebPDataClear(&webp_data);
+
+    // If we had to re-mux, we should free it now that we're done with it
+    if (mux != NULL) {
+        WebPMuxDelete(mux);
+    }
+
+    return ret;
+}
+
+// Decoder functions
+PyObject* _anim_decoder_new(PyObject* self, PyObject* args)
+{
+    PyBytesObject *webp_string;
+    const uint8_t *webp;
+    Py_ssize_t size;
+    WebPData webp_src;
+    char* mode;
+    WebPDecoderConfig config;
+    WebPAnimDecoderObject* decp = NULL;
+    WebPAnimDecoder* dec = NULL;
+
+    if (!PyArg_ParseTuple(args, "S", &webp_string)) {
+        return NULL;
+    }
+    PyBytes_AsStringAndSize((PyObject *)webp_string, (char**)&webp, &size);
+    webp_src.bytes = webp;
+    webp_src.size = size;
+
+    // Sniff the mode, since the decoder API doesn't tell us
+    mode = "RGBA";
+    if (WebPGetFeatures(webp, size, &config.input) == VP8_STATUS_OK) {
+        if (!config.input.has_alpha) {
+            mode = "RGBX";
+        }
+    }
+
+    // Create the decoder (default mode is RGBA, if no options passed)
+    decp = PyObject_New(WebPAnimDecoderObject, &WebPAnimDecoder_Type);
+    if (decp) {
+        decp->mode = mode;
+        if (WebPDataCopy(&webp_src, &(decp->data))) {
+            dec = WebPAnimDecoderNew(&(decp->data), NULL);
+            if (dec) {
+                if (WebPAnimDecoderGetInfo(dec, &(decp->info))) {
+                    decp->dec = dec;
+                    return (PyObject*)decp;
+                }
+            }
+        }
+        PyObject_Del(decp);
+    }
+    PyErr_SetString(PyExc_RuntimeError, "could not create decoder object");
+    return NULL;
+}
+
+PyObject* _anim_decoder_dealloc(PyObject* self)
+{
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject *)self;
+    WebPDataClear(&(decp->data));
+    WebPAnimDecoderDelete(decp->dec);
+    Py_RETURN_NONE;
+}
+
+PyObject* _anim_decoder_get_info(PyObject* self, PyObject* args)
+{
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject *)self;
+    WebPAnimInfo* info = &(decp->info);
+
+    return Py_BuildValue("IIIIIs",
+        info->canvas_width, info->canvas_height,
+        info->loop_count,
+        info->bgcolor,
+        info->frame_count,
+        decp->mode
+    );
+}
+
+PyObject* _anim_decoder_get_chunk(PyObject* self, PyObject* args)
+{
+    char* mode;
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject *)self;
+    const WebPDemuxer* demux;
+    WebPChunkIterator iter;
+    PyObject *ret;
+
+    if (!PyArg_ParseTuple(args, "s", &mode)) {
+        return NULL;
+    }
+
+    demux = WebPAnimDecoderGetDemuxer(decp->dec);
+    if (!WebPDemuxGetChunk(demux, mode, 1, &iter)) {
+        Py_RETURN_NONE;
+    }
+
+    ret = PyBytes_FromStringAndSize((const char*)iter.chunk.bytes, iter.chunk.size);
+    WebPDemuxReleaseChunkIterator(&iter);
+
+    return ret;
+}
+
+PyObject* _anim_decoder_get_next(PyObject* self, PyObject* args)
+{
+    uint8_t* buf;
+    int timestamp;
+    PyObject* bytes;
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject*)self;
+
+    if (!WebPAnimDecoderGetNext(decp->dec, &buf, &timestamp)) {
+        PyErr_SetString(PyExc_IOError, "failed to read next frame");
+        return NULL;
+    }
+
+    bytes = PyBytes_FromStringAndSize((char *)buf,
+        decp->info.canvas_width * 4 * decp->info.canvas_height);
+    return Py_BuildValue("Si", bytes, timestamp);
+}
+
+PyObject* _anim_decoder_has_more_frames(PyObject* self, PyObject* args)
+{
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject*)self;
+    return Py_BuildValue("i", WebPAnimDecoderHasMoreFrames(decp->dec));
+}
+
+PyObject* _anim_decoder_reset(PyObject* self, PyObject* args)
+{
+    WebPAnimDecoderObject* decp = (WebPAnimDecoderObject *)self;
+    WebPAnimDecoderReset(decp->dec);
+    Py_RETURN_NONE;
+}
+
+/* -------------------------------------------------------------------- */
+/* Type Definitions                                                     */
+/* -------------------------------------------------------------------- */
+
+// WebPAnimEncoder methods
+static struct PyMethodDef _anim_encoder_methods[] = {
+    {"add", (PyCFunction)_anim_encoder_add, METH_VARARGS, "add"},
+    {"assemble", (PyCFunction)_anim_encoder_assemble, METH_VARARGS, "assemble"},
+    {NULL, NULL} /* sentinel */
+};
+
+// WebPAnimDecoder type definition
+static PyTypeObject WebPAnimEncoder_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "WebPAnimEncoder",          /*tp_name */
+    sizeof(WebPAnimEncoderObject),   /*tp_size */
+    0,                          /*tp_itemsize */
+    /* methods */
+    (destructor)_anim_encoder_dealloc, /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare*/
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number */
+    0,                          /*tp_as_sequence */
+    0,                          /*tp_as_mapping */
+    0,                          /*tp_hash*/
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT,         /*tp_flags*/
+    0,                          /*tp_doc*/
+    0,                          /*tp_traverse*/
+    0,                          /*tp_clear*/
+    0,                          /*tp_richcompare*/
+    0,                          /*tp_weaklistoffset*/
+    0,                          /*tp_iter*/
+    0,                          /*tp_iternext*/
+    _anim_encoder_methods,      /*tp_methods*/
+    0,                          /*tp_members*/
+    0,     /*tp_getset*/
+};
+
+// WebPAnimDecoder methods
+static struct PyMethodDef _anim_decoder_methods[] = {
+    {"get_info", (PyCFunction)_anim_decoder_get_info, METH_VARARGS, "get_info"},
+    {"get_chunk", (PyCFunction)_anim_decoder_get_chunk, METH_VARARGS, "get_chunk"},
+    {"get_next", (PyCFunction)_anim_decoder_get_next, METH_VARARGS, "get_next"},
+    {"has_more_frames", (PyCFunction)_anim_decoder_has_more_frames, METH_VARARGS, "has_more_frames"},
+    {"reset", (PyCFunction)_anim_decoder_reset, METH_VARARGS, "reset"},
+    {NULL, NULL} /* sentinel */
+};
+
+// WebPAnimDecoder type definition
+static PyTypeObject WebPAnimDecoder_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "WebPAnimDecoder",          /*tp_name */
+    sizeof(WebPAnimDecoderObject),   /*tp_size */
+    0,                          /*tp_itemsize */
+    /* methods */
+    (destructor)_anim_decoder_dealloc, /*tp_dealloc*/
+    0,                          /*tp_print*/
+    0,                          /*tp_getattr*/
+    0,                          /*tp_setattr*/
+    0,                          /*tp_compare*/
+    0,                          /*tp_repr*/
+    0,                          /*tp_as_number */
+    0,                          /*tp_as_sequence */
+    0,                          /*tp_as_mapping */
+    0,                          /*tp_hash*/
+    0,                          /*tp_call*/
+    0,                          /*tp_str*/
+    0,                          /*tp_getattro*/
+    0,                          /*tp_setattro*/
+    0,                          /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT,         /*tp_flags*/
+    0,                          /*tp_doc*/
+    0,                          /*tp_traverse*/
+    0,                          /*tp_clear*/
+    0,                          /*tp_richcompare*/
+    0,                          /*tp_weaklistoffset*/
+    0,                          /*tp_iter*/
+    0,                          /*tp_iternext*/
+    _anim_decoder_methods,      /*tp_methods*/
+    0,                          /*tp_members*/
+    0,     /*tp_getset*/
+};
+
+#endif
+
+/* -------------------------------------------------------------------- */
+/* Legacy WebP Support                                                  */
+/* -------------------------------------------------------------------- */
+
 PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
 {
     int width;
     int height;
     int lossless;
     float quality_factor;
-    uint8_t *rgb;
-    uint8_t *icc_bytes;
-    uint8_t *exif_bytes;
-    uint8_t *output;
-    char *mode;
+    uint8_t* rgb;
+    uint8_t* icc_bytes;
+    uint8_t* exif_bytes;
+    uint8_t* xmp_bytes;
+    uint8_t* output;
+    char* mode;
     Py_ssize_t size;
     Py_ssize_t icc_size;
-    Py_ssize_t  exif_size;
+    Py_ssize_t exif_size;
+    Py_ssize_t xmp_size;
     size_t ret_size;
 
-    if (!PyArg_ParseTuple(args, PY_ARG_BYTES_LENGTH"iiifss#s#",
+    if (!PyArg_ParseTuple(args, PY_ARG_BYTES_LENGTH"iiifss#s#s#",
                 (char**)&rgb, &size, &width, &height, &lossless, &quality_factor, &mode,
-                &icc_bytes, &icc_size, &exif_bytes, &exif_size)) {
+                &icc_bytes, &icc_size, &exif_bytes, &exif_size, &xmp_bytes, &xmp_size)) {
         return NULL;
     }
     if (strcmp(mode, "RGBA")==0){
@@ -37,11 +561,11 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         }
         #if WEBP_ENCODER_ABI_VERSION >= 0x0100
         if (lossless) {
-            ret_size = WebPEncodeLosslessRGBA(rgb, width, height, 4* width, &output);
+            ret_size = WebPEncodeLosslessRGBA(rgb, width, height, 4 * width, &output);
         } else
         #endif
         {
-            ret_size = WebPEncodeRGBA(rgb, width, height, 4* width, quality_factor, &output);
+            ret_size = WebPEncodeRGBA(rgb, width, height, 4 * width, quality_factor, &output);
         }
     } else if (strcmp(mode, "RGB")==0){
         if (size < width * height * 3){
@@ -49,11 +573,11 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         }
         #if WEBP_ENCODER_ABI_VERSION >= 0x0100
         if (lossless) {
-            ret_size = WebPEncodeLosslessRGB(rgb, width, height, 3* width, &output);
+            ret_size = WebPEncodeLosslessRGB(rgb, width, height, 3 * width, &output);
         } else
         #endif
         {
-            ret_size = WebPEncodeRGB(rgb, width, height, 3* width, quality_factor, &output);
+            ret_size = WebPEncodeRGB(rgb, width, height, 3 * width, quality_factor, &output);
         }
     } else {
         Py_RETURN_NONE;
@@ -66,17 +590,19 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         return ret;
     }
 #else
-   {
-    /* I want to truncate the *_size items that get passed into webp
+    {
+    /* I want to truncate the *_size items that get passed into WebP
        data. Pypy2.1.0 had some issues where the Py_ssize_t items had
        data in the upper byte. (Not sure why, it shouldn't have been there)
     */
     int i_icc_size = (int)icc_size;
     int i_exif_size = (int)exif_size;
+    int i_xmp_size = (int)xmp_size;
     WebPData output_data = {0};
     WebPData image = { output, ret_size };
     WebPData icc_profile = { icc_bytes, i_icc_size };
     WebPData exif = { exif_bytes, i_exif_size };
+    WebPData xmp = { xmp_bytes, i_xmp_size };
     WebPMuxError err;
     int dbg = 0;
 
@@ -93,13 +619,11 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
 
     if (i_icc_size > 0) {
         if (dbg) {
-            fprintf (stderr, "Adding ICC Profile\n");
+            fprintf(stderr, "Adding ICC Profile\n");
         }
         err = WebPMuxSetChunk(mux, "ICCP", &icc_profile, copy_data);
-        if (dbg && err == WEBP_MUX_INVALID_ARGUMENT) {
-            fprintf(stderr, "Invalid ICC Argument\n");
-        } else if (dbg && err == WEBP_MUX_MEMORY_ERROR) {
-            fprintf(stderr, "ICC Memory Error\n");
+        if (err != WEBP_MUX_OK) {
+            return HandleMuxError(err, "ICCP");
         }
     }
 
@@ -107,14 +631,25 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
         fprintf(stderr, "exif size %d \n", i_exif_size);
     }
     if (i_exif_size > 0) {
-        if (dbg){
-            fprintf (stderr, "Adding Exif Data\n");
+        if (dbg) {
+            fprintf(stderr, "Adding Exif Data\n");
         }
         err = WebPMuxSetChunk(mux, "EXIF", &exif, copy_data);
-        if (dbg && err == WEBP_MUX_INVALID_ARGUMENT) {
-            fprintf(stderr, "Invalid Exif Argument\n");
-        } else if (dbg && err == WEBP_MUX_MEMORY_ERROR) {
-            fprintf(stderr, "Exif Memory Error\n");
+        if (err != WEBP_MUX_OK) {
+            return HandleMuxError(err, "EXIF");
+        }
+    }
+
+    if (dbg) {
+        fprintf(stderr, "xmp size %d \n", i_xmp_size);
+    }
+    if (i_xmp_size > 0) {
+        if (dbg){
+            fprintf(stderr, "Adding XMP Data\n");
+        }
+        err = WebPMuxSetChunk(mux, "XMP ", &xmp, copy_data);
+        if (err != WEBP_MUX_OK) {
+            return HandleMuxError(err, "XMP ");
         }
     }
 
@@ -133,11 +668,10 @@ PyObject* WebPEncode_wrapper(PyObject* self, PyObject* args)
     Py_RETURN_NONE;
 }
 
-
 PyObject* WebPDecode_wrapper(PyObject* self, PyObject* args)
 {
-    PyBytesObject *webp_string;
-    const uint8_t *webp;
+    PyBytesObject* webp_string;
+    const uint8_t* webp;
     Py_ssize_t size;
     PyObject *ret = Py_None, *bytes = NULL, *pymode = NULL, *icc_profile = NULL, *exif = NULL;
     WebPDecoderConfig config;
@@ -152,7 +686,7 @@ PyObject* WebPDecode_wrapper(PyObject* self, PyObject* args)
         Py_RETURN_NONE;
     }
 
-    PyBytes_AsStringAndSize((PyObject *) webp_string, (char**)&webp, &size);
+    PyBytes_AsStringAndSize((PyObject*) webp_string, (char**)&webp, &size);
 
     vp8_status_code = WebPGetFeatures(webp, size, &config.input);
     if (vp8_status_code == VP8_STATUS_OK) {
@@ -204,12 +738,12 @@ PyObject* WebPDecode_wrapper(PyObject* self, PyObject* args)
         goto end;
 
     if (config.output.colorspace < MODE_YUV) {
-        bytes = PyBytes_FromStringAndSize((char *)config.output.u.RGBA.rgba,
+        bytes = PyBytes_FromStringAndSize((char*)config.output.u.RGBA.rgba,
                                           config.output.u.RGBA.size);
     } else {
         // Skipping YUV for now. Need Test Images.
         // UNDONE -- unclear if we'll ever get here if we set mode_rgb*
-        bytes = PyBytes_FromStringAndSize((char *)config.output.u.YUVA.y,
+        bytes = PyBytes_FromStringAndSize((char*)config.output.u.YUVA.y,
                                           config.output.u.YUVA.y_size);
     }
 
@@ -255,8 +789,16 @@ PyObject* WebPDecoderBuggyAlpha_wrapper(PyObject* self, PyObject* args){
     return Py_BuildValue("i", WebPDecoderBuggyAlpha());
 }
 
+/* -------------------------------------------------------------------- */
+/* Module Setup                                                         */
+/* -------------------------------------------------------------------- */
+
 static PyMethodDef webpMethods[] =
 {
+#ifdef HAVE_WEBPANIM
+    {"WebPAnimDecoder", _anim_decoder_new, METH_VARARGS, "WebPAnimDecoder"},
+    {"WebPAnimEncoder", _anim_encoder_new, METH_VARARGS, "WebPAnimEncoder"},
+#endif
     {"WebPEncode", WebPEncode_wrapper, METH_VARARGS, "WebPEncode"},
     {"WebPDecode", WebPDecode_wrapper, METH_VARARGS, "WebPDecode"},
     {"WebPDecoderVersion", WebPDecoderVersion_wrapper, METH_VARARGS, "WebPVersion"},
@@ -272,11 +814,32 @@ void addMuxFlagToModule(PyObject* m) {
 #endif
 }
 
+void addAnimFlagToModule(PyObject* m) {
+#ifdef HAVE_WEBPANIM
+    PyModule_AddObject(m, "HAVE_WEBPANIM", Py_True);
+#else
+    PyModule_AddObject(m, "HAVE_WEBPANIM", Py_False);
+#endif
+}
+
 void addTransparencyFlagToModule(PyObject* m) {
     PyModule_AddObject(m, "HAVE_TRANSPARENCY",
 		       PyBool_FromLong(!WebPDecoderBuggyAlpha()));
 }
 
+static int setup_module(PyObject* m) {
+    addMuxFlagToModule(m);
+    addAnimFlagToModule(m);
+    addTransparencyFlagToModule(m);
+
+#ifdef HAVE_WEBPANIM
+    /* Ready object types */
+    if (PyType_Ready(&WebPAnimDecoder_Type) < 0 ||
+        PyType_Ready(&WebPAnimEncoder_Type) < 0)
+        return -1;
+#endif
+    return 0;
+}
 
 #if PY_VERSION_HEX >= 0x03000000
 PyMODINIT_FUNC
@@ -292,8 +855,9 @@ PyInit__webp(void) {
     };
 
     m = PyModule_Create(&module_def);
-    addMuxFlagToModule(m);
-    addTransparencyFlagToModule(m);
+    if (setup_module(m) < 0)
+        return NULL;
+
     return m;
 }
 #else
@@ -301,7 +865,6 @@ PyMODINIT_FUNC
 init_webp(void)
 {
     PyObject* m = Py_InitModule("_webp", webpMethods);
-    addMuxFlagToModule(m);
-    addTransparencyFlagToModule(m);
+    setup_module(m);
 }
 #endif
diff --git a/docs/handbook/image-file-formats.rst b/docs/handbook/image-file-formats.rst
index 7975c6900..130d15908 100644
--- a/docs/handbook/image-file-formats.rst
+++ b/docs/handbook/image-file-formats.rst
@@ -110,7 +110,7 @@ are available::
 **append_images**
     A list of images to append as additional frames. Each of the
     images in the list can be single or multiframe images.
-    This is currently only supported for GIF, PDF and TIFF.
+    This is currently only supported for GIF, PDF, TIFF, and WebP.
 
 **duration**
     The display duration of each frame of the multiframe gif, in
@@ -658,19 +658,69 @@ format are currently undocumented.
 The :py:meth:`~PIL.Image.Image.save` method supports the following options:
 
 **lossless**
-    If present and true, instructs the WEBP writer to use lossless compression.
+    If present and true, instructs the WebP writer to use lossless compression.
 
 **quality**
-    Integer, 1-100, Defaults to 80. Sets the quality level for
-    lossy compression.
+    Integer, 1-100, Defaults to 80. For lossy, 0 gives the smallest
+    size and 100 the largest. For lossless, this parameter is the amount
+    of effort put into the compression: 0 is the fastest, but gives larger
+    files compared to the slowest, but best, 100.
+
+**method**
+    Quality/speed trade-off (0=fast, 6=slower-better). Defaults to 0.
 
 **icc_procfile**
     The ICC Profile to include in the saved file. Only supported if
-    the system webp library was built with webpmux support.
+    the system WebP library was built with webpmux support.
 
 **exif**
     The exif data to include in the saved file. Only supported if
-    the system webp library was built with webpmux support.
+    the system WebP library was built with webpmux support.
+
+Saving sequences
+~~~~~~~~~~~~~~~~~
+
+.. note::
+
+    Support for animated WebP files will only be enabled if the system WebP
+    library is v0.5.0 or later. You can check webp animation support at
+    runtime by calling `features.check("webp_anim")`.
+
+When calling :py:meth:`~PIL.Image.Image.save`, the following options
+are available when the `save_all` argument is present and true.
+
+**append_images**
+    A list of images to append as additional frames. Each of the
+    images in the list can be single or multiframe images.
+
+**duration**
+    The display duration of each frame, in milliseconds. Pass a single
+    integer for a constant duration, or a list or tuple to set the
+    duration for each frame separately.
+
+**loop**
+    Number of times to repeat the animation. Defaults to [0 = infinite].
+
+**background**
+    Background color of the canvas, as an RGBA tuple with values in
+    the range of (0-255).
+
+**minimize_size**
+    If true, minimize the output size (slow). Implicitly disables
+    key-frame insertion.
+
+**kmin, kmax**
+    Minimum and maximum distance between consecutive key frames in
+    the output. The library may insert some key frames as needed
+    to satisfy this criteria. Note that these conditions should
+    hold: kmax > kmin and kmin >= kmax / 2 + 1. Also, if kmax <= 0,
+    then key-frame insertion is disabled; and if kmax == 1, then all
+    frames will be key-frames (kmin value does not matter for these
+    special cases).
+
+**allow_mixed**
+    If true, use mixed compression mode; the encoder heuristically
+    chooses between lossy and lossless for each frame.
 
 XBM
 ^^^
diff --git a/selftest.py b/selftest.py
index 108e57fd2..324d23b45 100755
--- a/selftest.py
+++ b/selftest.py
@@ -178,8 +178,9 @@ if __name__ == "__main__":
         ("freetype2", "FREETYPE2"),
         ("littlecms2", "LITTLECMS2"),
         ("webp", "WEBP"),
-        ("transp_webp", "Transparent WEBP"),
+        ("transp_webp", "WEBP Transparency"),
         ("webp_mux", "WEBPMUX"),
+        ("webp_anim", "WEBP Animation"),
         ("jpg", "JPEG"),
         ("jpg_2000", "OPENJPEG (JPEG2000)"),
         ("zlib", "ZLIB (PNG/ZIP)"),