diff --git a/django/forms/models.py b/django/forms/models.py
index 86eecee..0a32ffe 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -231,6 +231,26 @@ class BaseModelForm(BaseForm):
         return self.cleaned_data
 
     def validate_unique(self):
+        unique_checks, date_checks = self._get_unique_checks()
+        form_errors = []
+        bad_fields = set()
+
+        field_errors, global_errors = self._perform_unique_checks(unique_checks)
+        bad_fields.union(field_errors)
+        form_errors.extend(global_errors)
+
+        field_errors, global_errors = self._perform_date_checks(date_checks)
+        bad_fields.union(field_errors)
+        form_errors.extend(global_errors)
+
+        for field_name in bad_fields:
+            del self.cleaned_data[field_name]
+        if form_errors:
+            # Raise the unique together errors since they are considered
+            # form-wide.
+            raise ValidationError(form_errors)
+
+    def _get_unique_checks(self):
         from django.db.models.fields import FieldDoesNotExist, Field as ModelField
 
         # Gather a list of checks to perform. We only perform unique checks
@@ -271,24 +291,8 @@ class BaseModelForm(BaseForm):
                 date_checks.append(('year', name, f.unique_for_year))
             if f.unique_for_month and self.cleaned_data.get(f.unique_for_month) is not None:
                 date_checks.append(('month', name, f.unique_for_month))
+        return unique_checks, date_checks
 
-        form_errors = []
-        bad_fields = set()
-
-        field_errors, global_errors = self._perform_unique_checks(unique_checks)
-        bad_fields.union(field_errors)
-        form_errors.extend(global_errors)
-
-        field_errors, global_errors = self._perform_date_checks(date_checks)
-        bad_fields.union(field_errors)
-        form_errors.extend(global_errors)
-
-        for field_name in bad_fields:
-            del self.cleaned_data[field_name]
-        if form_errors:
-            # Raise the unique together errors since they are considered
-            # form-wide.
-            raise ValidationError(form_errors)
 
     def _perform_unique_checks(self, unique_checks):
         bad_fields = set()
@@ -504,6 +508,68 @@ class BaseModelFormSet(BaseFormSet):
             self.save_m2m = save_m2m
         return self.save_existing_objects(commit) + self.save_new_objects(commit)
 
+    def clean(self):
+        self.validate_unique()
+
+    def validate_unique(self):
+        for form in self.forms:
+            if hasattr(form, 'cleaned_data'):
+                break
+        else:
+            return
+        unique_checks, date_checks = form._get_unique_checks()
+        errors = []
+        for unique_check in unique_checks:
+            seen_data = set()
+            for form in self.forms:
+                if not hasattr(form, "cleaned_data"):
+                    continue
+                if [f for f in unique_check if f in form.cleaned_data and form.cleaned_data[f] is not None]:
+                    row_data = tuple([form.cleaned_data[field] for field in unique_check])
+                    if row_data in seen_data:
+                        errors.append(self.get_unique_error_message(unique_check))
+                        break
+                    seen_data.add(row_data)
+        for date_check in date_checks:
+            seen_data = set()
+            lookup, field, unique_for = date_check
+            for form in self.forms:
+                if not hasattr(self, 'cleaned_data'):
+                    continue
+                if (form.cleaned_data and form.cleaned_data[field] is not None
+                    and form.cleaned_data[unique_for] is not None):
+                    if lookup == 'date':
+                        date = form.cleaned_data[unique_for]
+                        date_data = (date.year, date.month, date.day)
+                    else:
+                        date_data = (getattr(form.cleaned_data[unique_for], lookup),)
+                    data = (form.cleaned_data[field],) + date_data
+                    if data in seen_data:
+                        errors.append(self.get_date_error_message(date_check))
+                        break
+                    seen_data.add(data)
+        if errors:
+            raise ValidationError(errors)
+
+    def get_unique_error_message(self, unique_check):
+        if len(unique_check) == 1:
+            return _("You have entered duplicate data for %(field)s. It "
+                "should be unique.") % {
+                    "field": unique_check[0],
+                }
+        else:
+            return _("You have entered duplicate data for %(field)s. They "
+                "should be unique together.") % {
+                    "field": get_text_list(unique_check, _("and")),
+                }
+
+    def get_date_error_message(self, date_check):
+        return _("%(field_name) data must be unique for %(date_field) %(lookup)s") % {
+            'field_name': unicode(date_check[1]),
+            'date_field': unicode(date_check[2]),
+            'lookup': unicode(date_check[0]),
+        }
+
     def save_existing_objects(self, commit=True):
         self.changed_objects = []
         self.deleted_objects = []
@@ -657,6 +723,10 @@ class BaseInlineFormSet(BaseModelFormSet):
                 label=getattr(form.fields.get(self.fk.name), 'label', capfirst(self.fk.verbose_name))
             )
 
+    def get_unique_error_message(self, unique_check):
+        unique_check = [field for field in unique_check if field != self.fk.name]
+        return super(BaseInlineFormSet, self).get_unique_error_message(unique_check)
+
 def _get_foreign_key(parent_model, model, fk_name=None):
     """
     Finds and returns the ForeignKey from model to parent if there is one.
diff --git a/docs/topics/forms/modelforms.txt b/docs/topics/forms/modelforms.txt
index be67a38..81d4642 100644
--- a/docs/topics/forms/modelforms.txt
+++ b/docs/topics/forms/modelforms.txt
@@ -515,6 +515,22 @@ exclude::
 
 .. _saving-objects-in-the-formset:
 
+Overriding clean() method
+-------------------------
+
+You can override the ``clean()`` method to provide custom validation to
+the whole formset at once. By default, the ``clean()`` method will validate
+that none of the data in the formsets violate the unique constraints on your
+model (both field ``unique`` and model ``unique_together``). To maintain this
+default behavior be sure you call the parent's ``clean()`` method::
+
+    class MyModelFormSet(BaseModelFormSet):
+        def clean(self):
+            super(MyModelFormSet, self).clean()
+            # example custom validation across forms in the formset:
+            for form in self.forms:
+                # your custom formset validation
+
 Saving objects in the formset
 -----------------------------
 
@@ -599,6 +615,17 @@ than that of a "normal" formset. The only difference is that we call
 ``formset.save()`` to save the data into the database. (This was described
 above, in :ref:`saving-objects-in-the-formset`.)
 
+
+Overiding ``clean()`` on a ``model_formset``
+--------------------------------------------
+
+Just like with ``ModelForms``, by default the ``clean()`` method of a 
+``model_formset`` will validate that none of the items in the formset validate 
+the unique constraints on your model(either unique or unique_together).  If you 
+want to overide the ``clean()`` method on a ``model_formset`` and maintain this 
+validation, you must call the parent classes ``clean`` method.
+
+
 Using a custom queryset
 ~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/modeltests/model_formsets/models.py b/tests/modeltests/model_formsets/models.py
index f30b212..3455cee 100644
--- a/tests/modeltests/model_formsets/models.py
+++ b/tests/modeltests/model_formsets/models.py
@@ -23,6 +23,12 @@ class Book(models.Model):
     author = models.ForeignKey(Author)
     title = models.CharField(max_length=100)
 
+    class Meta:
+        unique_together = (
+            ('author', 'title'),
+        )
+        ordering = ['id']
+
     def __unicode__(self):
         return self.title
 
@@ -58,7 +64,7 @@ class CustomPrimaryKey(models.Model):
 class Place(models.Model):
     name = models.CharField(max_length=50)
     city = models.CharField(max_length=50)
-    
+
     def __unicode__(self):
         return self.name
 
@@ -85,7 +91,7 @@ class OwnerProfile(models.Model):
 
 class Restaurant(Place):
     serves_pizza = models.BooleanField()
-    
+
     def __unicode__(self):
         return self.name
 
@@ -573,7 +579,7 @@ True
 ...     print book.title
 Les Fleurs du Mal
 
-Test inline formsets where the inline-edited object uses multi-table inheritance, thus 
+Test inline formsets where the inline-edited object uses multi-table inheritance, thus
 has a non AutoField yet auto-created primary key.
 
 >>> AuthorBooksFormSet3 = inlineformset_factory(Author, AlternateBook, can_delete=False, extra=1)
@@ -740,7 +746,7 @@ True
 >>> formset.save()
 [<OwnerProfile: Joe Perry is 55>]
 
-# ForeignKey with unique=True should enforce max_num=1 
+# ForeignKey with unique=True should enforce max_num=1
 
 >>> FormSet = inlineformset_factory(Place, Location, can_delete=False)
 >>> formset = FormSet(instance=place)
@@ -943,4 +949,68 @@ True
 >>> FormSet = modelformset_factory(ClassyMexicanRestaurant, fields=["tacos_are_yummy"])
 >>> sorted(FormSet().forms[0].fields.keys())
 ['restaurant', 'tacos_are_yummy']
+
+# Prevent duplicates from within the same formset
+>>> FormSet = modelformset_factory(Product, extra=2)
+>>> data = {
+...     'form-TOTAL_FORMS': 2,
+...     'form-INITIAL_FORMS': 0,
+...     'form-0-slug': 'red_car',
+...     'form-1-slug': 'red_car',
+... }
+>>> formset = FormSet(data)
+>>> formset.is_valid()
+False
+>>> formset._non_form_errors
+[u'You have entered duplicate data for slug. It should be unique.']
+
+>>> FormSet = modelformset_factory(Price, extra=2)
+>>> data = {
+...     'form-TOTAL_FORMS': 2,
+...     'form-INITIAL_FORMS': 0,
+...     'form-0-price': '25',
+...     'form-0-quantity': '7',
+...     'form-1-price': '25',
+...     'form-1-quantity': '7',
+... }
+>>> formset = FormSet(data)
+>>> formset.is_valid()
+False
+>>> formset._non_form_errors
+[u'You have entered duplicate data for price and quantity. They should be unique together.']
+
+# only the price field is specified, this should skip any unique checks since the unique_together is not fulfilled.
+# this will fail with a KeyError if broken.
+>>> FormSet = modelformset_factory(Price, fields=("price",), extra=2)
+>>> data = {
+...     'form-TOTAL_FORMS': '2',
+...     'form-INITIAL_FORMS': '0',
+...     'form-0-price': '24',
+...     'form-1-price': '24',
+... }
+>>> formset = FormSet(data)
+>>> formset.is_valid()
+True
+
+>>> FormSet = inlineformset_factory(Author, Book, extra=0)
+>>> author = Author.objects.order_by('id')[0]
+>>> book_ids = author.book_set.values_list('id', flat=True)
+>>> data = {
+...     'book_set-TOTAL_FORMS': '2',
+...     'book_set-INITIAL_FORMS': '2',
+...
+...     'book_set-0-title': 'The 2008 Election',
+...     'book_set-0-author': str(author.id),
+...     'book_set-0-id': str(book_ids[0]),
+...
+...     'book_set-1-title': 'The 2008 Election',
+...     'book_set-1-author': str(author.id),
+...     'book_set-1-id': str(book_ids[1]),
+... }
+>>> formset = FormSet(data=data, instance=author)
+>>> formset.is_valid()
+False
+>>> formset._non_form_errors
+[u'You have entered duplicate data for title. It should be unique.']
+
 """}
