diff --git a/README.md b/README.md
index 3d8dce948..049f9075e 100644
--- a/README.md
+++ b/README.md
@@ -57,9 +57,17 @@ To run the tests.
 
 # Changelog
 
-## Master
+## 2.1.0
 
-* Minor field improvements (don't stringify dicts, more robust many-pk fields)
+**Date**: 5th Nov 2012
+
+**Warning**: Please read [this thread][2.1.0-notes] regarding the `instance` and `data` keyword args before updating to 2.1.0.
+
+* **Serializer `instance` and `data` keyword args have their position swapped.**
+* `queryset` argument is now optional on writable model fields.
+* Support Django's cache framework.
+* Minor field improvements. (Don't stringify dicts, more robust many-pk fields.)
+* Bugfixes (Support choice field in Browseable API)
 
 ## 2.0.2
 
@@ -113,6 +121,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 [0.4]: https://github.com/tomchristie/django-rest-framework/tree/0.4.X
 [sandbox]: http://restframework.herokuapp.com/
 [rest-framework-2-announcement]: topics/rest-framework-2-announcement.md
+[2.1.0-notes]: https://groups.google.com/d/topic/django-rest-framework/Vv2M0CMY9bg/discussion
 
 [docs]: http://django-rest-framework.org/
 [urlobject]: https://github.com/zacharyvoase/urlobject
diff --git a/docs/api-guide/serializers.md b/docs/api-guide/serializers.md
index c88b9b0c6..ee7f72dd7 100644
--- a/docs/api-guide/serializers.md
+++ b/docs/api-guide/serializers.md
@@ -47,7 +47,7 @@ The first part of serializer class defines the fields that get serialized/deseri
 
 We can now use `CommentSerializer` to serialize a comment, or list of comments.  Again, using the `Serializer` class looks a lot like using a `Form` class.
 
-    serializer = CommentSerializer(instance=comment)
+    serializer = CommentSerializer(comment)
     serializer.data
     # {'email': u'leila@example.com', 'content': u'foo bar', 'created': datetime.datetime(2012, 8, 22, 16, 20, 9, 822774)}
 
@@ -65,20 +65,29 @@ Deserialization is similar.  First we parse a stream into python native datatype
 
 ...then we restore those native datatypes into a fully populated object instance.
 
-    serializer = CommentSerializer(data)
+    serializer = CommentSerializer(data=data)
     serializer.is_valid()
     # True
     serializer.object
     # <Comment object at 0x10633b2d0>
     >>> serializer.deserialize('json', stream)
 
+When deserializing data, we can either create a new instance, or update an existing instance.
+
+    serializer = CommentSerializer(data=data)           # Create new instance
+    serializer = CommentSerializer(comment, data=data)  # Update `instance`
+
 ## Validation
 
 When deserializing data, you always need to call `is_valid()` before attempting to access the deserialized object.  If any validation errors occur, the `.errors` and `.non_field_errors` properties will contain the resulting error messages.
 
 ### Field-level validation
 
-You can specify custom field-level validation by adding `validate_<fieldname>()` methods to your `Serializer` subclass. These are analagous to `clean_<fieldname>` methods on Django forms, but accept slightly different arguments. They take a dictionary of deserialized attributes as a first argument, and the field name in that dictionary as a second argument (which will be either the name of the field or the value of the `source` argument to the field, if one was provided). Your `validate_<fieldname>` methods should either just return the attrs dictionary or raise a `ValidationError`. For example:
+You can specify custom field-level validation by adding `.validate_<fieldname>` methods to your `Serializer` subclass. These are analagous to `.clean_<fieldname>` methods on Django forms, but accept slightly different arguments.
+
+They take a dictionary of deserialized attributes as a first argument, and the field name in that dictionary as a second argument (which will be either the name of the field or the value of the `source` argument to the field, if one was provided).
+
+Your `validate_<fieldname>` methods should either just return the `attrs` dictionary or raise a `ValidationError`. For example:
 
     from rest_framework import serializers
 
@@ -88,16 +97,22 @@ You can specify custom field-level validation by adding `validate_<fieldname>()`
 
         def validate_title(self, attrs, source):
             """
-            Check that the blog post is about Django
+            Check that the blog post is about Django.
             """
             value = attrs[source]
-            if "Django" not in value:
+            if "django" not in value.lower():
                 raise serializers.ValidationError("Blog post is not about Django")
             return attrs
 
-### Final cross-field validation
+### Object-level validation
 
-To do any other validation that requires access to multiple fields, add a method called `validate` to your `Serializer` subclass. This method takes a single argument, which is the `attrs` dictionary. It should raise a `ValidationError` if necessary, or just return `attrs`.
+To do any other validation that requires access to multiple fields, add a method called `.validate()` to your `Serializer` subclass. This method takes a single argument, which is the `attrs` dictionary. It should raise a `ValidationError` if necessary, or just return `attrs`.
+
+## Saving object state
+
+Serializers also include a `.save()` method that you can override if you want to provide a method of persisting the state of a deserialized object.  The default behavior of the method is to simply call `.save()` on the deserialized object instance.
+
+The generic views provided by REST framework call the `.save()` method when updating or creating entities.  
 
 ## Dealing with nested objects
 
diff --git a/docs/topics/release-notes.md b/docs/topics/release-notes.md
index 14d910bd9..6e7008f1f 100644
--- a/docs/topics/release-notes.md
+++ b/docs/topics/release-notes.md
@@ -4,11 +4,18 @@
 >
 > &mdash; Eric S. Raymond, [The Cathedral and the Bazaar][cite].
 
-## Master
+## 2.1.0
 
+**Date**: 5th Nov 2012
+
+**Warning**: Please read [this thread][2.1.0-notes] regarding the `instance` and `data` keyword args before updating to 2.1.0.
+
+* **Serializer `instance` and `data` keyword args have their position swapped.**
+* `queryset` argument is now optional on writable model fields.
 * Support Django's cache framework.
 * Minor field improvements. (Don't stringify dicts, more robust many-pk fields.)
-* Bugfixes (Support choice field in Browseable API)
+* Bugfix: Support choice field in Browseable API.
+* Bugfix: Related fields with `read_only=True` do not require a `queryset` argument.
 
 ## 2.0.2
 
@@ -29,7 +36,7 @@
 **Date**: 30th Oct 2012
 
 * **Fix all of the things.**  (Well, almost.)
-* For more information please see the [2.0 migration guide][migration].
+* For more information please see the [2.0 announcement][announcement].
 
 ---
 
@@ -135,4 +142,5 @@
 * Initial release.
 
 [cite]: http://www.catb.org/~esr/writings/cathedral-bazaar/cathedral-bazaar/ar01s04.html
-[migration]: migration.md
\ No newline at end of file
+[2.1.0-notes]: https://groups.google.com/d/topic/django-rest-framework/Vv2M0CMY9bg/discussion
+[announcement]: rest-framework-2-announcement.md
\ No newline at end of file
diff --git a/docs/tutorial/1-serialization.md b/docs/tutorial/1-serialization.md
index 316a3c255..ba64f2aa7 100644
--- a/docs/tutorial/1-serialization.md
+++ b/docs/tutorial/1-serialization.md
@@ -162,7 +162,7 @@ Okay, once we've got a few imports out of the way, let's create a code snippet t
 
 We've now got a few snippet instances to play with.  Let's take a look at serializing one of those instances.
 
-    serializer = SnippetSerializer(instance=snippet)
+    serializer = SnippetSerializer(snippet)
     serializer.data
     # {'pk': 1, 'title': u'', 'code': u'print "hello, world"\n', 'linenos': False, 'language': u'python', 'style': u'friendly'}
 
@@ -181,7 +181,7 @@ Deserialization is similar.  First we parse a stream into python native datatype
 
 ...then we restore those native datatypes into to a fully populated object instance.
 
-    serializer = SnippetSerializer(data)
+    serializer = SnippetSerializer(data=data)
     serializer.is_valid()
     # True
     serializer.object
@@ -240,12 +240,12 @@ The root of our API is going to be a view that supports listing all the existing
         """
         if request.method == 'GET':
             snippets = Snippet.objects.all()
-            serializer = SnippetSerializer(instance=snippets)
+            serializer = SnippetSerializer(snippets)
             return JSONResponse(serializer.data)
 
         elif request.method == 'POST':
             data = JSONParser().parse(request)
-            serializer = SnippetSerializer(data)
+            serializer = SnippetSerializer(data=data)
             if serializer.is_valid():
                 serializer.save()
                 return JSONResponse(serializer.data, status=201)
@@ -267,12 +267,12 @@ We'll also need a view which corresponds to an individual snippet, and can be us
             return HttpResponse(status=404)
  
         if request.method == 'GET':
-            serializer = SnippetSerializer(instance=snippet)
+            serializer = SnippetSerializer(snippet)
             return JSONResponse(serializer.data)
     
         elif request.method == 'PUT':
             data = JSONParser().parse(request)
-            serializer = SnippetSerializer(data, instance=snippet)
+            serializer = SnippetSerializer(snippet, data=data)
             if serializer.is_valid():
                 serializer.save()
                 return JSONResponse(serializer.data)
diff --git a/docs/tutorial/2-requests-and-responses.md b/docs/tutorial/2-requests-and-responses.md
index a7c23cba6..b29daf05a 100644
--- a/docs/tutorial/2-requests-and-responses.md
+++ b/docs/tutorial/2-requests-and-responses.md
@@ -52,11 +52,11 @@ We don't need our `JSONResponse` class anymore, so go ahead and delete that.  On
         """
         if request.method == 'GET':
             snippets = Snippet.objects.all()
-            serializer = SnippetSerializer(instance=snippets)
+            serializer = SnippetSerializer(snippets)
             return Response(serializer.data)
 
         elif request.method == 'POST':
-            serializer = SnippetSerializer(request.DATA)
+            serializer = SnippetSerializer(data=request.DATA)
             if serializer.is_valid():
                 serializer.save()
                 return Response(serializer.data, status=status.HTTP_201_CREATED)
@@ -77,11 +77,11 @@ Our instance view is an improvement over the previous example.  It's a little mo
             return Response(status=status.HTTP_404_NOT_FOUND)
  
         if request.method == 'GET':
-            serializer = SnippetSerializer(instance=snippet)
+            serializer = SnippetSerializer(snippet)
             return Response(serializer.data)
     
         elif request.method == 'PUT':
-            serializer = SnippetSerializer(request.DATA, instance=snippet)
+            serializer = SnippetSerializer(snippet, data=request.DATA)
             if serializer.is_valid():
                 serializer.save()
                 return Response(serializer.data)
diff --git a/docs/tutorial/3-class-based-views.md b/docs/tutorial/3-class-based-views.md
index 91ef40387..eddf63110 100644
--- a/docs/tutorial/3-class-based-views.md
+++ b/docs/tutorial/3-class-based-views.md
@@ -20,11 +20,11 @@ We'll start by rewriting the root view as a class based view.  All this involves
         """
         def get(self, request, format=None):
             snippets = Snippet.objects.all()
-            serializer = SnippetSerializer(instance=snippets)
+            serializer = SnippetSerializer(snippets)
             return Response(serializer.data)
 
         def post(self, request, format=None):
-            serializer = SnippetSerializer(request.DATA)
+            serializer = SnippetSerializer(data=request.DATA)
             if serializer.is_valid():
                 serializer.save()
                 return Response(serializer.data, status=status.HTTP_201_CREATED)
@@ -44,12 +44,12 @@ So far, so good.  It looks pretty similar to the previous case, but we've got be
 
         def get(self, request, pk, format=None):
             snippet = self.get_object(pk)
-            serializer = SnippetSerializer(instance=snippet)
+            serializer = SnippetSerializer(snippet)
             return Response(serializer.data)
 
         def put(self, request, pk, format=None):
             snippet = self.get_object(pk)
-            serializer = SnippetSerializer(request.DATA, instance=snippet)
+            serializer = SnippetSerializer(snippet, data=request.DATA)
             if serializer.is_valid():
                 serializer.save()
                 return Response(serializer.data)
diff --git a/docs/tutorial/5-relationships-and-hyperlinked-apis.md b/docs/tutorial/5-relationships-and-hyperlinked-apis.md
index 3113249b5..98c45b821 100644
--- a/docs/tutorial/5-relationships-and-hyperlinked-apis.md
+++ b/docs/tutorial/5-relationships-and-hyperlinked-apis.md
@@ -167,7 +167,7 @@ We've reached the end of our tutorial.  If you want to get more involved in the
 * Join the [REST framework discussion group][group], and help build the community.
 * Follow the author [on Twitter][twitter] and say hi.
 
-**Now go build some awesome things.**
+**Now go build awesome things.**
 
 [repo]: https://github.com/tomchristie/rest-framework-tutorial
 [sandbox]: http://restframework.herokuapp.com/
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index eb4c5e1f2..dc726a326 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -40,7 +40,7 @@ class Field(object):
 
         self.source = source
 
-    def initialize(self, parent):
+    def initialize(self, parent, field_name):
         """
         Called to set up a field prior to field_to_native or field_from_native.
 
@@ -248,7 +248,22 @@ class RelatedField(WritableField):
     def __init__(self, *args, **kwargs):
         self.queryset = kwargs.pop('queryset', None)
         super(RelatedField, self).__init__(*args, **kwargs)
-        self.read_only = self.default_read_only
+        self.read_only = kwargs.pop('read_only', self.default_read_only)
+
+    def initialize(self, parent, field_name):
+        super(RelatedField, self).initialize(parent, field_name)
+        if self.queryset is None and not self.read_only:
+            try:
+                manager = getattr(self.parent.opts.model, self.source or field_name)
+                if hasattr(manager, 'related'):  # Forward
+                    self.queryset = manager.related.model._default_manager.all()
+                else:  # Reverse
+                    self.queryset = manager.field.rel.to._default_manager.all()
+            except:
+                raise
+                msg = ('Serializer related fields must include a `queryset`' +
+                       ' argument or set `read_only=True')
+                raise Exception(msg)
 
     ### We need this stuff to make form choices work...
 
diff --git a/rest_framework/generics.py b/rest_framework/generics.py
index 27540a57f..7675d7f99 100644
--- a/rest_framework/generics.py
+++ b/rest_framework/generics.py
@@ -48,7 +48,7 @@ class GenericAPIView(views.APIView):
         # TODO: add support for seperate serializer/deserializer
         serializer_class = self.get_serializer_class()
         context = self.get_serializer_context()
-        return serializer_class(data, instance=instance, context=context)
+        return serializer_class(instance, data=data, context=context)
 
 
 class MultipleObjectAPIView(MultipleObjectMixin, GenericAPIView):
diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index 3d134a741..28767b16b 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -6,6 +6,15 @@ from django.db import models
 from django.forms import widgets
 from django.utils.datastructures import SortedDict
 from rest_framework.compat import get_concrete_model
+
+# Note: We do the following so that users of the framework can use this style:
+#
+#     example_field = serializers.CharField(...)
+#
+# This helps keep the seperation between model fields, form fields, and
+# serializer fields more explicit.
+
+
 from rest_framework.fields import *
 
 
@@ -82,10 +91,10 @@ class BaseSerializer(Field):
     _options_class = SerializerOptions
     _dict_class = SortedDictWithMetadata  # Set to unsorted dict for backwards compatability with unsorted implementations.
 
-    def __init__(self, data=None, instance=None, context=None, **kwargs):
+    def __init__(self, instance=None, data=None, context=None, **kwargs):
         super(BaseSerializer, self).__init__(**kwargs)
-        self.fields = copy.deepcopy(self.base_fields)
         self.opts = self._options_class(self.Meta)
+        self.fields = copy.deepcopy(self.base_fields)
         self.parent = None
         self.root = None
 
@@ -100,13 +109,13 @@ class BaseSerializer(Field):
     #####
     # Methods to determine which fields to use when (de)serializing objects.
 
-    def default_fields(self, serialize, obj=None, data=None, nested=False):
+    def default_fields(self, nested=False):
         """
         Return the complete set of default fields for the object, as a dict.
         """
         return {}
 
-    def get_fields(self, serialize, obj=None, data=None, nested=False):
+    def get_fields(self, nested=False):
         """
         Returns the complete set of fields for the object as a dict.
 
@@ -119,10 +128,10 @@ class BaseSerializer(Field):
         for key, field in self.fields.items():
             ret[key] = field
             # Set up the field
-            field.initialize(parent=self)
+            field.initialize(parent=self, field_name=key)
 
         # Add in the default fields
-        fields = self.default_fields(serialize, obj, data, nested)
+        fields = self.default_fields(nested)
         for key, val in fields.items():
             if key not in ret:
                 ret[key] = val
@@ -144,12 +153,12 @@ class BaseSerializer(Field):
     #####
     # Field methods - used when the serializer class is itself used as a field.
 
-    def initialize(self, parent):
+    def initialize(self, parent, field_name):
         """
         Same behaviour as usual Field, except that we need to keep track
         of state so that we can deal with handling maximum depth.
         """
-        super(BaseSerializer, self).initialize(parent)
+        super(BaseSerializer, self).initialize(parent, field_name)
         if parent.opts.depth:
             self.opts.depth = parent.opts.depth - 1
 
@@ -170,7 +179,7 @@ class BaseSerializer(Field):
         ret = self._dict_class()
         ret.fields = {}
 
-        fields = self.get_fields(serialize=True, obj=obj, nested=bool(self.opts.depth))
+        fields = self.get_fields(nested=bool(self.opts.depth))
         for field_name, field in fields.items():
             key = self.get_field_key(field_name)
             value = field.field_to_native(obj, field_name)
@@ -183,7 +192,7 @@ class BaseSerializer(Field):
         Core of deserialization, together with `restore_object`.
         Converts a dictionary of data into a dictionary of deserialized fields.
         """
-        fields = self.get_fields(serialize=False, data=data, nested=bool(self.opts.depth))
+        fields = self.get_fields(nested=bool(self.opts.depth))
         reverted_data = {}
         for field_name, field in fields.items():
             try:
@@ -198,7 +207,7 @@ class BaseSerializer(Field):
         Run `validate_<fieldname>()` and `validate()` methods on the serializer
         """
         # TODO: refactor this so we're not determining the fields again
-        fields = self.get_fields(serialize=False, data=attrs, nested=bool(self.opts.depth))
+        fields = self.get_fields(nested=bool(self.opts.depth))
 
         for field_name, field in fields.items():
             try:
@@ -237,11 +246,8 @@ class BaseSerializer(Field):
         """
         Serialize objects -> primatives.
         """
-        if isinstance(obj, dict):
-            return dict([(key, self.to_native(val))
-                         for (key, val) in obj.items()])
-        elif hasattr(obj, '__iter__'):
-            return [self.to_native(item) for item in obj]
+        if hasattr(obj, '__iter__'):
+            return [self.convert_object(item) for item in obj]
         return self.convert_object(obj)
 
     def from_native(self, data):
@@ -323,7 +329,7 @@ class ModelSerializer(Serializer):
     """
     _options_class = ModelSerializerOptions
 
-    def default_fields(self, serialize, obj=None, data=None, nested=False):
+    def default_fields(self, nested=False):
         """
         Return all the fields that should be serialized for the model.
         """
@@ -360,7 +366,7 @@ class ModelSerializer(Serializer):
                 field = self.get_field(model_field)
 
             if field:
-                field.initialize(parent=self)
+                field.initialize(parent=self, field_name=model_field.name)
                 ret[model_field.name] = field
 
         return ret
diff --git a/rest_framework/tests/genericrelations.py b/rest_framework/tests/genericrelations.py
index 1d7e33bcb..bc7378e12 100644
--- a/rest_framework/tests/genericrelations.py
+++ b/rest_framework/tests/genericrelations.py
@@ -25,7 +25,7 @@ class TestGenericRelations(TestCase):
                 model = Bookmark
                 exclude = ('id',)
 
-        serializer = BookmarkSerializer(instance=self.bookmark)
+        serializer = BookmarkSerializer(self.bookmark)
         expected = {
             'tags': [u'django', u'python'],
             'url': u'https://www.djangoproject.com/'
diff --git a/rest_framework/tests/hyperlinkedserializers.py b/rest_framework/tests/hyperlinkedserializers.py
index 92c3691e1..147943c6f 100644
--- a/rest_framework/tests/hyperlinkedserializers.py
+++ b/rest_framework/tests/hyperlinkedserializers.py
@@ -7,12 +7,13 @@ from rest_framework.tests.models import Anchor, BasicModel, ManyToManyModel, Blo
 factory = RequestFactory()
 
 
-class BlogPostCommentSerializer(serializers.Serializer):
+class BlogPostCommentSerializer(serializers.ModelSerializer):
     text = serializers.CharField()
-    blog_post_url = serializers.HyperlinkedRelatedField(source='blog_post', view_name='blogpost-detail', queryset=BlogPost.objects.all())
+    blog_post_url = serializers.HyperlinkedRelatedField(source='blog_post', view_name='blogpost-detail')
 
-    def restore_object(self, attrs, instance=None):
-        return BlogPostComment(**attrs)
+    class Meta:
+        model = BlogPostComment
+        fields = ('text', 'blog_post_url')
 
 
 class BasicList(generics.ListCreateAPIView):
@@ -42,7 +43,7 @@ class ManyToManyDetail(generics.RetrieveAPIView):
 
 class BlogPostCommentListCreate(generics.ListCreateAPIView):
     model = BlogPostComment
-    model_serializer_class = BlogPostCommentSerializer
+    serializer_class = BlogPostCommentSerializer
 
 
 class BlogPostDetail(generics.RetrieveAPIView):
diff --git a/rest_framework/tests/pagination.py b/rest_framework/tests/pagination.py
index a939c9ef5..64e8d822f 100644
--- a/rest_framework/tests/pagination.py
+++ b/rest_framework/tests/pagination.py
@@ -74,13 +74,13 @@ class UnitTestPagination(TestCase):
         self.last_page = paginator.page(3)
 
     def test_native_pagination(self):
-        serializer = pagination.PaginationSerializer(instance=self.first_page)
+        serializer = pagination.PaginationSerializer(self.first_page)
         self.assertEquals(serializer.data['count'], 26)
         self.assertEquals(serializer.data['next'], '?page=2')
         self.assertEquals(serializer.data['previous'], None)
         self.assertEquals(serializer.data['results'], self.objects[:10])
 
-        serializer = pagination.PaginationSerializer(instance=self.last_page)
+        serializer = pagination.PaginationSerializer(self.last_page)
         self.assertEquals(serializer.data['count'], 26)
         self.assertEquals(serializer.data['next'], None)
         self.assertEquals(serializer.data['previous'], '?page=2')
diff --git a/rest_framework/tests/pk_relations.py b/rest_framework/tests/pk_relations.py
index 9095dcd81..947098107 100644
--- a/rest_framework/tests/pk_relations.py
+++ b/rest_framework/tests/pk_relations.py
@@ -15,7 +15,7 @@ class ManyToManySource(models.Model):
 
 
 class ManyToManyTargetSerializer(serializers.ModelSerializer):
-    sources = serializers.ManyPrimaryKeyRelatedField(queryset=ManyToManySource.objects.all())
+    sources = serializers.ManyPrimaryKeyRelatedField()
 
     class Meta:
         model = ManyToManyTarget
@@ -63,7 +63,7 @@ class PrimaryKeyManyToManyTests(TestCase):
 
     def test_many_to_many_retrieve(self):
         queryset = ManyToManySource.objects.all()
-        serializer = ManyToManySourceSerializer(instance=queryset)
+        serializer = ManyToManySourceSerializer(queryset)
         expected = [
                 {'id': 1, 'name': u'source-1', 'targets': [1]},
                 {'id': 2, 'name': u'source-2', 'targets': [1, 2]},
@@ -73,7 +73,7 @@ class PrimaryKeyManyToManyTests(TestCase):
 
     def test_reverse_many_to_many_retrieve(self):
         queryset = ManyToManyTarget.objects.all()
-        serializer = ManyToManyTargetSerializer(instance=queryset)
+        serializer = ManyToManyTargetSerializer(queryset)
         expected = [
             {'id': 1, 'name': u'target-1', 'sources': [1, 2, 3]},
             {'id': 2, 'name': u'target-2', 'sources': [2, 3]},
@@ -84,14 +84,14 @@ class PrimaryKeyManyToManyTests(TestCase):
     def test_many_to_many_update(self):
         data = {'id': 1, 'name': u'source-1', 'targets': [1, 2, 3]}
         instance = ManyToManySource.objects.get(pk=1)
-        serializer = ManyToManySourceSerializer(data, instance=instance)
+        serializer = ManyToManySourceSerializer(instance, data=data)
         self.assertTrue(serializer.is_valid())
         self.assertEquals(serializer.data, data)
         serializer.save()
 
         # Ensure source 1 is updated, and everything else is as expected
         queryset = ManyToManySource.objects.all()
-        serializer = ManyToManySourceSerializer(instance=queryset)
+        serializer = ManyToManySourceSerializer(queryset)
         expected = [
                 {'id': 1, 'name': u'source-1', 'targets': [1, 2, 3]},
                 {'id': 2, 'name': u'source-2', 'targets': [1, 2]},
@@ -102,14 +102,14 @@ class PrimaryKeyManyToManyTests(TestCase):
     def test_reverse_many_to_many_update(self):
         data = {'id': 1, 'name': u'target-1', 'sources': [1]}
         instance = ManyToManyTarget.objects.get(pk=1)
-        serializer = ManyToManyTargetSerializer(data, instance=instance)
+        serializer = ManyToManyTargetSerializer(instance, data=data)
         self.assertTrue(serializer.is_valid())
         self.assertEquals(serializer.data, data)
         serializer.save()
 
         # Ensure target 1 is updated, and everything else is as expected
         queryset = ManyToManyTarget.objects.all()
-        serializer = ManyToManyTargetSerializer(instance=queryset)
+        serializer = ManyToManyTargetSerializer(queryset)
         expected = [
             {'id': 1, 'name': u'target-1', 'sources': [1]},
             {'id': 2, 'name': u'target-2', 'sources': [2, 3]},
@@ -130,7 +130,7 @@ class PrimaryKeyForeignKeyTests(TestCase):
 
     def test_foreign_key_retrieve(self):
         queryset = ForeignKeySource.objects.all()
-        serializer = ForeignKeySourceSerializer(instance=queryset)
+        serializer = ForeignKeySourceSerializer(queryset)
         expected = [
             {'id': 1, 'name': u'source-1', 'target': 1},
             {'id': 2, 'name': u'source-2', 'target': 1},
@@ -140,7 +140,7 @@ class PrimaryKeyForeignKeyTests(TestCase):
 
     def test_reverse_foreign_key_retrieve(self):
         queryset = ForeignKeyTarget.objects.all()
-        serializer = ForeignKeyTargetSerializer(instance=queryset)
+        serializer = ForeignKeyTargetSerializer(queryset)
         expected = [
             {'id': 1, 'name': u'target-1', 'sources': [1, 2, 3]},
             {'id': 2, 'name': u'target-2', 'sources': []},
@@ -150,14 +150,14 @@ class PrimaryKeyForeignKeyTests(TestCase):
     def test_foreign_key_update(self):
         data = {'id': 1, 'name': u'source-1', 'target': 2}
         instance = ForeignKeySource.objects.get(pk=1)
-        serializer = ForeignKeySourceSerializer(data, instance=instance)
+        serializer = ForeignKeySourceSerializer(instance, data=data)
         self.assertTrue(serializer.is_valid())
         self.assertEquals(serializer.data, data)
         serializer.save()
 
         # # Ensure source 1 is updated, and everything else is as expected
         queryset = ForeignKeySource.objects.all()
-        serializer = ForeignKeySourceSerializer(instance=queryset)
+        serializer = ForeignKeySourceSerializer(queryset)
         expected = [
             {'id': 1, 'name': u'source-1', 'target': 2},
             {'id': 2, 'name': u'source-2', 'target': 1},
@@ -172,14 +172,14 @@ class PrimaryKeyForeignKeyTests(TestCase):
     # def test_reverse_foreign_key_update(self):
     #     data = {'id': 1, 'name': u'target-1', 'sources': [1]}
     #     instance = ForeignKeyTarget.objects.get(pk=1)
-    #     serializer = ForeignKeyTargetSerializer(data, instance=instance)
+    #     serializer = ForeignKeyTargetSerializer(instance, data=data)
     #     self.assertTrue(serializer.is_valid())
     #     self.assertEquals(serializer.data, data)
     #     serializer.save()
 
     #     # Ensure target 1 is updated, and everything else is as expected
     #     queryset = ForeignKeyTarget.objects.all()
-    #     serializer = ForeignKeyTargetSerializer(instance=queryset)
+    #     serializer = ForeignKeyTargetSerializer(queryset)
     #     expected = [
     #         {'id': 1, 'name': u'target-1', 'sources': [1]},
     #         {'id': 2, 'name': u'target-2', 'sources': []},
diff --git a/rest_framework/tests/serializer.py b/rest_framework/tests/serializer.py
index 3fd490644..8d1de4298 100644
--- a/rest_framework/tests/serializer.py
+++ b/rest_framework/tests/serializer.py
@@ -87,11 +87,11 @@ class BasicTests(TestCase):
         self.assertEquals(serializer.data, expected)
 
     def test_retrieve(self):
-        serializer = CommentSerializer(instance=self.comment)
+        serializer = CommentSerializer(self.comment)
         self.assertEquals(serializer.data, self.expected)
 
     def test_create(self):
-        serializer = CommentSerializer(self.data)
+        serializer = CommentSerializer(data=self.data)
         expected = self.comment
         self.assertEquals(serializer.is_valid(), True)
         self.assertEquals(serializer.object, expected)
@@ -99,25 +99,25 @@ class BasicTests(TestCase):
         self.assertEquals(serializer.data['sub_comment'], 'And Merry Christmas!')
 
     def test_update(self):
-        serializer = CommentSerializer(self.data, instance=self.comment)
+        serializer = CommentSerializer(self.comment, data=self.data)
         expected = self.comment
         self.assertEquals(serializer.is_valid(), True)
         self.assertEquals(serializer.object, expected)
         self.assertTrue(serializer.object is expected)
         self.assertEquals(serializer.data['sub_comment'], 'And Merry Christmas!')
-    
+
     def test_model_fields_as_expected(self):
         """ Make sure that the fields returned are the same as defined
         in the Meta data
         """
-        serializer = PersonSerializer(instance=self.person)
+        serializer = PersonSerializer(self.person)
         self.assertEquals(set(serializer.data.keys()),
                           set(['name', 'age', 'info']))
 
     def test_field_with_dictionary(self):
         """ Make sure that dictionaries from fields are left intact
         """
-        serializer = PersonSerializer(instance=self.person)
+        serializer = PersonSerializer(self.person)
         expected = self.person_data
         self.assertEquals(serializer.data['info'], expected)
 
@@ -138,12 +138,12 @@ class ValidationTests(TestCase):
         )
 
     def test_create(self):
-        serializer = CommentSerializer(self.data)
+        serializer = CommentSerializer(data=self.data)
         self.assertEquals(serializer.is_valid(), False)
         self.assertEquals(serializer.errors, {'content': [u'Ensure this value has at most 1000 characters (it has 1001).']})
 
     def test_update(self):
-        serializer = CommentSerializer(self.data, instance=self.comment)
+        serializer = CommentSerializer(self.comment, data=self.data)
         self.assertEquals(serializer.is_valid(), False)
         self.assertEquals(serializer.errors, {'content': [u'Ensure this value has at most 1000 characters (it has 1001).']})
 
@@ -152,7 +152,7 @@ class ValidationTests(TestCase):
             'content': 'xxx',
             'created': datetime.datetime(2012, 1, 1)
         }
-        serializer = CommentSerializer(data, instance=self.comment)
+        serializer = CommentSerializer(self.comment, data=data)
         self.assertEquals(serializer.is_valid(), False)
         self.assertEquals(serializer.errors, {'email': [u'This field is required.']})
 
@@ -163,7 +163,7 @@ class ValidationTests(TestCase):
             'title': 'Some action item',
             #No 'done' value.
         }
-        serializer = ActionItemSerializer(data, instance=self.actionitem)
+        serializer = ActionItemSerializer(self.actionitem, data=data)
         self.assertEquals(serializer.is_valid(), True)
         self.assertEquals(serializer.errors, {})
 
@@ -183,12 +183,12 @@ class ValidationTests(TestCase):
             'created': datetime.datetime(2012, 1, 1)
         }
 
-        serializer = CommentSerializerWithFieldValidator(data)
+        serializer = CommentSerializerWithFieldValidator(data=data)
         self.assertTrue(serializer.is_valid())
 
         data['content'] = 'This should not validate'
 
-        serializer = CommentSerializerWithFieldValidator(data)
+        serializer = CommentSerializerWithFieldValidator(data=data)
         self.assertFalse(serializer.is_valid())
         self.assertEquals(serializer.errors, {'content': [u'Test not in value']})
 
@@ -207,12 +207,12 @@ class ValidationTests(TestCase):
             'created': datetime.datetime(2012, 1, 1)
         }
 
-        serializer = CommentSerializerWithCrossFieldValidator(data)
+        serializer = CommentSerializerWithCrossFieldValidator(data=data)
         self.assertTrue(serializer.is_valid())
 
         data['content'] = 'A comment from foo@bar.com'
 
-        serializer = CommentSerializerWithCrossFieldValidator(data)
+        serializer = CommentSerializerWithCrossFieldValidator(data=data)
         self.assertFalse(serializer.is_valid())
         self.assertEquals(serializer.errors, {'non_field_errors': [u'Email address not in content']})
 
@@ -220,7 +220,7 @@ class ValidationTests(TestCase):
         """
         Omitting a value for null-field should validate.
         """
-        serializer = PersonSerializer({'name': 'marko'})
+        serializer = PersonSerializer(data={'name': 'marko'})
         self.assertEquals(serializer.is_valid(), True)
         self.assertEquals(serializer.errors, {})
 
@@ -270,7 +270,7 @@ class ManyToManyTests(TestCase):
         Create an instance of a model with a ManyToMany relationship.
         """
         data = {'rel': [self.anchor.id]}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ManyToManyModel.objects.all()), 2)
@@ -284,7 +284,7 @@ class ManyToManyTests(TestCase):
         new_anchor = Anchor()
         new_anchor.save()
         data = {'rel': [self.anchor.id, new_anchor.id]}
-        serializer = self.serializer_class(data, instance=self.instance)
+        serializer = self.serializer_class(self.instance, data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ManyToManyModel.objects.all()), 1)
@@ -297,7 +297,7 @@ class ManyToManyTests(TestCase):
         containing no items.
         """
         data = {'rel': []}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ManyToManyModel.objects.all()), 2)
@@ -312,7 +312,7 @@ class ManyToManyTests(TestCase):
         new_anchor = Anchor()
         new_anchor.save()
         data = {'rel': []}
-        serializer = self.serializer_class(data, instance=self.instance)
+        serializer = self.serializer_class(self.instance, data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ManyToManyModel.objects.all()), 1)
@@ -326,7 +326,7 @@ class ManyToManyTests(TestCase):
         lists (eg form data).
         """
         data = {'rel': ''}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ManyToManyModel.objects.all()), 2)
@@ -364,7 +364,7 @@ class ReadOnlyManyToManyTests(TestCase):
         new_anchor = Anchor()
         new_anchor.save()
         data = {'rel': [self.anchor.id, new_anchor.id]}
-        serializer = self.serializer_class(data, instance=self.instance)
+        serializer = self.serializer_class(self.instance, data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ReadOnlyManyToManyModel.objects.all()), 1)
@@ -380,7 +380,7 @@ class ReadOnlyManyToManyTests(TestCase):
         new_anchor = Anchor()
         new_anchor.save()
         data = {}
-        serializer = self.serializer_class(data, instance=self.instance)
+        serializer = self.serializer_class(self.instance, data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(ReadOnlyManyToManyModel.objects.all()), 1)
@@ -400,7 +400,7 @@ class DefaultValueTests(TestCase):
 
     def test_create_using_default(self):
         data = {}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(self.objects.all()), 1)
@@ -409,7 +409,7 @@ class DefaultValueTests(TestCase):
 
     def test_create_overriding_default(self):
         data = {'text': 'overridden'}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(self.objects.all()), 1)
@@ -428,7 +428,7 @@ class CallableDefaultValueTests(TestCase):
 
     def test_create_using_default(self):
         data = {}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(self.objects.all()), 1)
@@ -437,7 +437,7 @@ class CallableDefaultValueTests(TestCase):
 
     def test_create_overriding_default(self):
         data = {'text': 'overridden'}
-        serializer = self.serializer_class(data)
+        serializer = self.serializer_class(data=data)
         self.assertEquals(serializer.is_valid(), True)
         instance = serializer.save()
         self.assertEquals(len(self.objects.all()), 1)
@@ -499,11 +499,11 @@ class BlankFieldTests(TestCase):
         self.data = {'title': ''}
 
     def test_create_blank_field(self):
-        serializer = self.serializer_class(self.data)
+        serializer = self.serializer_class(data=self.data)
         self.assertEquals(serializer.is_valid(), True)
 
     def test_create_model_blank_field(self):
-        serializer = self.model_serializer_class(self.data)
+        serializer = self.model_serializer_class(data=self.data)
         self.assertEquals(serializer.is_valid(), True)
 
     def test_create_not_blank_field(self):
@@ -511,7 +511,7 @@ class BlankFieldTests(TestCase):
         Test to ensure blank data in a field not marked as blank=True
         is considered invalid in a non-model serializer
         """
-        serializer = self.not_blank_serializer_class(self.data)
+        serializer = self.not_blank_serializer_class(data=self.data)
         self.assertEquals(serializer.is_valid(), False)
 
     def test_create_model_not_blank_field(self):
@@ -519,5 +519,5 @@ class BlankFieldTests(TestCase):
         Test to ensure blank data in a field not marked as blank=True
         is considered invalid in a model serializer
         """
-        serializer = self.not_blank_model_serializer_class(self.data)
+        serializer = self.not_blank_model_serializer_class(data=self.data)
         self.assertEquals(serializer.is_valid(), False)