diff --git a/django/core/management.py b/django/core/management.py
index a163c83c5d..ea572729d9 100644
--- a/django/core/management.py
+++ b/django/core/management.py
@@ -855,7 +855,7 @@ def get_validation_errors(outfile, app=None):
             if f.rel:
                 rel_opts = f.rel.to._meta
                 if f.rel.to not in models.get_models():
-                    e.add(opts, "'%s' has relation with uninstalled model %s" % (f.name, rel_opts.object_name))
+                    e.add(opts, "'%s' has relation with model %s, which has not been installed" % (f.name, rel_opts.object_name))
 
                 rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name()
                 for r in rel_opts.fields:
@@ -876,7 +876,7 @@ def get_validation_errors(outfile, app=None):
             # existing fields, m2m fields, m2m related objects or related objects
             rel_opts = f.rel.to._meta
             if f.rel.to not in models.get_models():
-                e.add(opts, "'%s' has m2m relation with uninstalled model %s" % (f.name, rel_opts.object_name))
+                e.add(opts, "'%s' has m2m relation with model %s, which has not been installed" % (f.name, rel_opts.object_name))
 
             rel_name = RelatedObject(f.rel.to, cls, f).get_accessor_name()
             for r in rel_opts.fields:
diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index f9750217a2..3863e75993 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -1,5 +1,5 @@
 from django.db import backend, connection, transaction
-from django.db.models import signals
+from django.db.models import signals, get_model
 from django.db.models.fields import AutoField, Field, IntegerField, get_ul_class
 from django.db.models.related import RelatedObject
 from django.utils.translation import gettext_lazy, string_concat
@@ -23,7 +23,12 @@ def add_lookup(rel_cls, field):
     name = field.rel.to
     module = rel_cls.__module__
     key = (module, name)
-    pending_lookups.setdefault(key, []).append((rel_cls, field))
+    model = get_model(rel_cls._meta.app_label,field.rel.to)
+    if model:
+        field.rel.to = model
+        field.do_related_class(model, rel_cls)
+    else:
+        pending_lookups.setdefault(key, []).append((rel_cls, field))
 
 def do_pending_lookups(sender):
     other_cls = sender
diff --git a/django/db/models/loading.py b/django/db/models/loading.py
index 7f5c97924b..4eafc22fb4 100644
--- a/django/db/models/loading.py
+++ b/django/db/models/loading.py
@@ -5,36 +5,45 @@ from django.core.exceptions import ImproperlyConfigured
 
 __all__ = ('get_apps', 'get_app', 'get_models', 'get_model', 'register_models')
 
-_app_list = None # Cache of installed apps.
+_app_list = []   # Cache of installed apps.
+                 # Entry is not placed in app_list cache until entire app is loaded.
 _app_models = {} # Dictionary of models against app label
                  # Each value is a dictionary of model name: model class
+                 # Applabel and Model entry exists in cache when individual model is loaded.
+_loaded = False  # Has the contents of settings.INSTALLED_APPS been loaded? 
+                 # i.e., has get_apps() been called?
 
 def get_apps():
     "Returns a list of all installed modules that contain models."
     global _app_list
-    if _app_list is not None:
-        return _app_list
-    _app_list = []
-    for app_name in settings.INSTALLED_APPS:
-        try:
-            mod = __import__(app_name, '', '', ['models'])
-        except ImportError:
-            pass # Assume this app doesn't have a models.py in it.
-                 # GOTCHA: It may have a models.py that raises ImportError.
-        else:
+    global _loaded
+    if not _loaded:
+        _loaded = True
+        for app_name in settings.INSTALLED_APPS:
             try:
-                _app_list.append(mod.models)
+                load_app(app_name)
+            except ImportError:
+                pass # Assume this app doesn't have a models.py in it.
+                     # GOTCHA: It may have a models.py that raises ImportError.
             except AttributeError:
                 pass # This app doesn't have a models.py in it.
     return _app_list
 
 def get_app(app_label):
     "Returns the module containing the models for the given app_label."
+    get_apps() # Run get_apps() to populate the _app_list cache. Slightly hackish.
     for app_name in settings.INSTALLED_APPS:
         if app_label == app_name.split('.')[-1]:
-            return __import__(app_name, '', '', ['models']).models
+            return load_app(app_name)
     raise ImproperlyConfigured, "App with label %s could not be found" % app_label
 
+def load_app(app_name):
+    "Loads the app with the provided fully qualified name, and returns the model module."
+    mod = __import__(app_name, '', '', ['models'])
+    if mod.models not in _app_list:
+        _app_list.append(mod.models)
+    return mod.models
+    
 def get_models(app_mod=None):
     """
     Given a module containing models, returns a list of the models. Otherwise
diff --git a/tests/regressiontests/string_lookup/__init__.py b/tests/regressiontests/string_lookup/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/regressiontests/string_lookup/models.py b/tests/regressiontests/string_lookup/models.py
new file mode 100644
index 0000000000..7dd31f572d
--- /dev/null
+++ b/tests/regressiontests/string_lookup/models.py
@@ -0,0 +1,48 @@
+from django.db import models
+
+class Foo(models.Model):
+    name = models.CharField(maxlength=50)
+
+    def __str__(self):
+        return "Foo %s" % self.name
+
+class Bar(models.Model):
+    name = models.CharField(maxlength=50)
+    normal = models.ForeignKey(Foo, related_name='normal_foo')
+    fwd = models.ForeignKey("Whiz")
+    back = models.ForeignKey("Foo")
+
+    def __str__(self):
+        return "Bar %s" % self.place.name
+
+class Whiz(models.Model):
+    name = models.CharField(maxlength = 50)
+
+    def __str__(self):
+        return "Whiz %s" % self.name
+
+API_TESTS = """
+# Regression test for #1662: Check that string form referencing of models works, both as
+# pre and post reference
+
+>>> f1 = Foo(name="Foo1")
+>>> f1.save()
+>>> f2 = Foo(name="Foo1")
+>>> f2.save()
+
+>>> w1 = Whiz(name="Whiz1")
+>>> w1.save()
+
+>>> b1 = Bar(name="Bar1", normal=f1, fwd=w1, back=f2)
+>>> b1.save()
+
+>>> b1.normal
+<Foo: Foo Foo1>
+
+>>> b1.fwd
+<Whiz: Whiz Whiz1>
+
+>>> b1.back
+<Foo: Foo Foo1>
+
+"""
diff --git a/tests/runtests.py b/tests/runtests.py
index 291ee15f7d..e5e9c18fca 100755
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -162,10 +162,11 @@ class TestRunner:
         # Initialize the test database.
         cursor = connection.cursor()
 
+        from django.db.models.loading import load_app
         # Install the core always installed apps
         for app in ALWAYS_INSTALLED_APPS:
             self.output(1, "Installing contrib app %s" % app)
-            mod = __import__(app + ".models", '', '', [''])
+            mod = load_app(app)
             management.install(mod)
 
         # Run the tests for each test model.
@@ -173,8 +174,7 @@ class TestRunner:
         for model_dir, model_name in test_models:
             self.output(1, "%s model: Importing" % model_name)
             try:
-                # TODO: Abstract this into a meta.get_app() replacement?
-                mod = __import__(model_dir + '.' + model_name + '.models', '', '', [''])
+                mod = load_app(model_dir + '.' + model_name)
             except Exception, e:
                 log_error(model_name, "Error while importing", ''.join(traceback.format_exception(*sys.exc_info())[1:]))
                 continue