diff --git a/Code/CoreData/RKManagedObjectStore.m b/Code/CoreData/RKManagedObjectStore.m
index 3bdccefd..568ffa28 100644
--- a/Code/CoreData/RKManagedObjectStore.m
+++ b/Code/CoreData/RKManagedObjectStore.m
@@ -309,7 +309,10 @@ static NSString* const RKManagedObjectStoreThreadDictionaryEntityCacheKey = @"RK
     NSAssert(primaryKeyAttribute, @"Cannot find existing managed object instance without a primary key attribute");
     NSAssert(primaryKeyValue, @"Cannot find existing managed object by primary key without a value");
 	NSManagedObject* object = nil;
-        
+    
+    // NOTE: We coerce the primary key into a string (if possible) for convenience. Generally
+    // primary keys are expressed either as a number of a string, so this lets us support either case interchangeably
+    id lookupValue = [primaryKeyValue respondsToSelector:@selector(stringValue)] ? [primaryKeyValue stringValue] : primaryKeyValue;
     NSArray* objects = nil;
     NSString* entityName = entity.name;
     NSMutableDictionary* threadDictionary = [[NSThread currentThread] threadDictionary];
@@ -327,10 +330,13 @@ static NSString* const RKManagedObjectStoreThreadDictionaryEntityCacheKey = @"RK
         objects = [NSManagedObject executeFetchRequest:fetchRequest];
         RKLogInfo(@"Caching all %d %@ objects to thread local storage", [objects count], entity.name);
         NSMutableDictionary* dictionary = [NSMutableDictionary dictionary];
+        BOOL coerceToString = [[[objects lastObject] valueForKey:primaryKeyAttribute] respondsToSelector:@selector(stringValue)];
         for (id theObject in objects) {			
-            id primaryKeyValue = [theObject valueForKey:primaryKeyAttribute];
+            id attributeValue = [theObject valueForKey:primaryKeyAttribute];
+            // Coerce to a string if possible
+            attributeValue = coerceToString ? [attributeValue stringValue] : attributeValue;
             if (primaryKeyValue) {
-                [dictionary setObject:theObject forKey:primaryKeyValue];
+                [dictionary setObject:theObject forKey:attributeValue];
             }
         }
         
@@ -339,7 +345,7 @@ static NSString* const RKManagedObjectStoreThreadDictionaryEntityCacheKey = @"RK
     
     NSMutableDictionary* dictionary = [entityCache objectForKey:entityName];
     NSAssert1(dictionary, @"Thread local cache of %@ objects should not be nil", entityName);
-    object = [dictionary objectForKey:primaryKeyValue];
+    object = [dictionary objectForKey:lookupValue];
     
     if (object == nil) {
         object = [[[NSManagedObject alloc] initWithEntity:entity insertIntoManagedObjectContext:self.managedObjectContext] autorelease];
diff --git a/RestKit.xcodeproj/project.pbxproj b/RestKit.xcodeproj/project.pbxproj
index 3a78d9cd..082ceac9 100644
--- a/RestKit.xcodeproj/project.pbxproj
+++ b/RestKit.xcodeproj/project.pbxproj
@@ -36,6 +36,7 @@
 		250C296C13411E60000A3551 /* RKRequestQueueSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 250C296B13411E60000A3551 /* RKRequestQueueSpec.m */; };
 		250C29FD134185D2000A3551 /* RKNetwork.h in Headers */ = {isa = PBXBuildFile; fileRef = 250C29FB134185CE000A3551 /* RKNetwork.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		250C29FE134185D2000A3551 /* RKNetwork.m in Sources */ = {isa = PBXBuildFile; fileRef = 250C29FC134185D0000A3551 /* RKNetwork.m */; };
+		250CAF5813BF9F2D00A1330E /* RKManagedObjectStoreSpec.m in Sources */ = {isa = PBXBuildFile; fileRef = 250CAF5713BF9F2D00A1330E /* RKManagedObjectStoreSpec.m */; };
 		250D5BF013A0698100471F0E /* lcl.h in Headers */ = {isa = PBXBuildFile; fileRef = 250D5BDB13A0698100471F0E /* lcl.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		250D5BF113A0698100471F0E /* lcl.m in Sources */ = {isa = PBXBuildFile; fileRef = 250D5BDC13A0698100471F0E /* lcl.m */; };
 		250D5BFA13A0698100471F0E /* LCLNSLog.h in Headers */ = {isa = PBXBuildFile; fileRef = 250D5BE913A0698100471F0E /* LCLNSLog.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -392,6 +393,7 @@
 		250C296B13411E60000A3551 /* RKRequestQueueSpec.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RKRequestQueueSpec.m; sourceTree = "<group>"; };
 		250C29FB134185CE000A3551 /* RKNetwork.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RKNetwork.h; sourceTree = "<group>"; };
 		250C29FC134185D0000A3551 /* RKNetwork.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RKNetwork.m; sourceTree = "<group>"; };
+		250CAF5713BF9F2D00A1330E /* RKManagedObjectStoreSpec.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RKManagedObjectStoreSpec.m; sourceTree = "<group>"; };
 		250D5BDB13A0698100471F0E /* lcl.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = lcl.h; sourceTree = "<group>"; };
 		250D5BDC13A0698100471F0E /* lcl.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = lcl.m; sourceTree = "<group>"; };
 		250D5BDD13A0698100471F0E /* lcl_config_components.template.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = lcl_config_components.template.h; sourceTree = "<group>"; };
@@ -1334,6 +1336,7 @@
 				25901D7B137B695F0002ECEB /* RKManagedObjectFactorySpec.m */,
 				257FB68613958786003A628E /* RKManagedObjectMappingSpec.m */,
 				257FB70C1395DEB5003A628E /* RKManagedObjectMappingOperationSpec.m */,
+				250CAF5713BF9F2D00A1330E /* RKManagedObjectStoreSpec.m */,
 			);
 			path = CoreData;
 			sourceTree = "<group>";
@@ -2120,6 +2123,7 @@
 				2515E7BD13B36AC100E013A4 /* RKObjectLoaderSpecResultModel.m in Sources */,
 				25ACF1AD13BB9D490067B380 /* RKURLSpec.m in Sources */,
 				2559209713BD1B8700E9C29C /* RKParamsSpec.m in Sources */,
+				250CAF5813BF9F2D00A1330E /* RKManagedObjectStoreSpec.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
diff --git a/RestKit.xcodeproj/xcshareddata/xcschemes/UISpec.xcscheme b/RestKit.xcodeproj/xcshareddata/xcschemes/UISpec.xcscheme
index 9f913e09..e20d4052 100644
--- a/RestKit.xcodeproj/xcshareddata/xcschemes/UISpec.xcscheme
+++ b/RestKit.xcodeproj/xcshareddata/xcschemes/UISpec.xcscheme
@@ -87,13 +87,13 @@
          </EnvironmentVariable>
          <EnvironmentVariable
             key = "UISPEC_SPEC"
-            value = "RKObjectLoaderSpec"
-            isEnabled = "YES">
+            value = "RKManagedObjectStoreSpec"
+            isEnabled = "NO">
          </EnvironmentVariable>
          <EnvironmentVariable
             key = "UISPEC_EXAMPLE"
             value = "itShouldRespectTheRootKeyPathWhenConstructingATemporaryObjectMappingProvider"
-            isEnabled = "YES">
+            isEnabled = "NO">
          </EnvironmentVariable>
          <EnvironmentVariable
             key = "NSAutoreleaseHaltOnNoPool"
diff --git a/Specs/CoreData/RKManagedObjectStoreSpec.m b/Specs/CoreData/RKManagedObjectStoreSpec.m
new file mode 100644
index 00000000..dfadf545
--- /dev/null
+++ b/Specs/CoreData/RKManagedObjectStoreSpec.m
@@ -0,0 +1,27 @@
+//
+//  RKManagedObjectStoreSpec.m
+//  RestKit
+//
+//  Created by Blake Watters on 7/2/11.
+//  Copyright 2011 Two Toasters. All rights reserved.
+//
+
+#import "RKSpecEnvironment.h"
+#import "RKHuman.h"
+
+@interface RKManagedObjectStoreSpec : RKSpec
+
+@end
+
+@implementation RKManagedObjectStoreSpec
+
+- (void)itShouldCoercePrimaryKeysToStringsForLookup {
+    RKManagedObjectStore* objectStore = RKSpecNewManagedObjectStore();
+    RKHuman* human = [RKHuman createEntity];
+    human.railsID = [NSNumber numberWithInt:1234];
+    [objectStore save];
+    NSManagedObject* newReference = [objectStore findOrCreateInstanceOfEntity:[RKHuman entity] withPrimaryKeyAttribute:@"railsID" andValue:@"1234"];
+    assertThat(newReference, is(equalTo(human)));
+}
+
+@end