diff --git a/django/views/generic/edit.py b/django/views/generic/edit.py
index 3cade522d4..d107e9a732 100644
--- a/django/views/generic/edit.py
+++ b/django/views/generic/edit.py
@@ -19,7 +19,7 @@ class FormMixin(object):
         """
         Returns the initial data to use for forms on this view.
         """
-        return self.initial
+        return self.initial.copy()
 
     def get_form_class(self):
         """
diff --git a/docs/ref/class-based-views.txt b/docs/ref/class-based-views.txt
index e1ff28977d..5223aee018 100644
--- a/docs/ref/class-based-views.txt
+++ b/docs/ref/class-based-views.txt
@@ -431,9 +431,14 @@ FormMixin
 
     .. method:: get_initial()
 
-        Retrieve initial data for the form. By default, returns
+        Retrieve initial data for the form. By default, returns a copy of
         :attr:`.initial`.
 
+    .. admonition:: Changed in 1.4
+
+        In Django 1.3, this method was returning the :attr:`initial` class
+        variable itself.
+
     .. method:: get_form_class()
 
         Retrieve the form class to instantiate. By default
diff --git a/docs/releases/1.4.txt b/docs/releases/1.4.txt
index d82ca03d28..211d1362c8 100644
--- a/docs/releases/1.4.txt
+++ b/docs/releases/1.4.txt
@@ -1107,6 +1107,15 @@ passed to the markdown filter, both the ``safe_mode=True`` and
 Python-Markdown library less than 2.1, a warning is issued that the output is
 insecure.
 
+FormMixin get_initial returns an instance-specific dictionary
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In Django 1.3, the ``get_initial`` method of the
+:class:`django.views.generic.edit.FormMixin` class was returning the
+class ``initial`` dictionary. This has been fixed to return a copy of this
+dictionary, so form instances can modify their initial data without messing
+with the class variable.
+
 Features deprecated in 1.4
 ==========================
 
diff --git a/tests/regressiontests/generic_views/edit.py b/tests/regressiontests/generic_views/edit.py
index 2bd982e3d9..651e14fff3 100644
--- a/tests/regressiontests/generic_views/edit.py
+++ b/tests/regressiontests/generic_views/edit.py
@@ -5,11 +5,20 @@ from django.core.urlresolvers import reverse
 from django import forms
 from django.test import TestCase
 from django.utils.unittest import expectedFailure
+from django.views.generic.edit import FormMixin
 
 from . import views
 from .models import Artist, Author
 
 
+class FormMixinTests(TestCase):
+     def test_initial_data(self):
+         """ Test instance independence of initial data dict (see #16138) """
+         initial_1 = FormMixin().get_initial()
+         initial_1['foo'] = 'bar'
+         initial_2 = FormMixin().get_initial()
+         self.assertNotEqual(initial_1, initial_2)
+
 class ModelFormMixinTests(TestCase):
     def test_get_form(self):
         form_class = views.AuthorGetQuerySetFormView().get_form_class()
diff --git a/tests/regressiontests/generic_views/tests.py b/tests/regressiontests/generic_views/tests.py
index d387216d41..72aab035a8 100644
--- a/tests/regressiontests/generic_views/tests.py
+++ b/tests/regressiontests/generic_views/tests.py
@@ -5,6 +5,6 @@ from .dates import (ArchiveIndexViewTests, YearArchiveViewTests,
     MonthArchiveViewTests, WeekArchiveViewTests, DayArchiveViewTests,
     DateDetailViewTests)
 from .detail import DetailViewTest
-from .edit import (ModelFormMixinTests, CreateViewTests, UpdateViewTests,
-    DeleteViewTests)
+from .edit import (FormMixinTests, ModelFormMixinTests, CreateViewTests,
+    UpdateViewTests, DeleteViewTests)
 from .list import ListViewTests