diff --git a/runtime/class_table.h b/runtime/class_table.h
new file mode 100644
index 0000000..af25131
--- /dev/null
+++ b/runtime/class_table.h
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_CLASS_TABLE_H_
+#define ART_RUNTIME_CLASS_TABLE_H_
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/allocator.h"
+#include "base/hash_set.h"
+#include "base/macros.h"
+#include "base/mutex.h"
+#include "dex_file.h"
+#include "gc_root.h"
+#include "object_callbacks.h"
+#include "runtime.h"
+
+namespace art {
+
+namespace mirror {
+  class ClassLoader;
+}  // namespace mirror
+
+typedef bool (ClassVisitor)(mirror::Class* c, void* arg);
+
+// Each loader has a ClassTable
+class ClassTable {
+ public:
+  ClassTable();
+
+  // Used by image writer for checking.
+  bool Contains(mirror::Class* klass)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Freeze the current class tables by allocating a new table and never updating or modifying the
+  // existing table. This helps prevents dirty pages after caused by inserting after zygote fork.
+  void FreezeSnapshot()
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Returns the number of classes in previous snapshots.
+  size_t NumZygoteClasses() const REQUIRES(Locks::classlinker_classes_lock_);
+
+  // Returns all off the classes in the lastest snapshot.
+  size_t NumNonZygoteClasses() const REQUIRES(Locks::classlinker_classes_lock_);
+
+  // Update a class in the table with the new class. Returns the existing class which was replaced.
+  mirror::Class* UpdateClass(const char* descriptor, mirror::Class* new_klass, size_t hash)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  void VisitRoots(RootVisitor* visitor, VisitRootFlags flags)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Return false if the callback told us to exit.
+  bool Visit(ClassVisitor* visitor, void* arg)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  mirror::Class* Lookup(const char* descriptor, size_t hash)
+      SHARED_REQUIRES(Locks::classlinker_classes_lock_, Locks::mutator_lock_);
+
+  void Insert(mirror::Class* klass)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+  void InsertWithHash(mirror::Class* klass, size_t hash)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+  // Returns true if the class was found and removed, false otherwise.
+  bool Remove(const char* descriptor)
+      REQUIRES(Locks::classlinker_classes_lock_) SHARED_REQUIRES(Locks::mutator_lock_);
+
+ private:
+  class ClassDescriptorHashEquals {
+   public:
+    // Same class loader and descriptor.
+    std::size_t operator()(const GcRoot<mirror::Class>& root) const NO_THREAD_SAFETY_ANALYSIS;
+    bool operator()(const GcRoot<mirror::Class>& a, const GcRoot<mirror::Class>& b) const
+        NO_THREAD_SAFETY_ANALYSIS;;
+    // Same descriptor.
+    bool operator()(const GcRoot<mirror::Class>& a, const char* descriptor) const
+        NO_THREAD_SAFETY_ANALYSIS;
+    std::size_t operator()(const char* descriptor) const NO_THREAD_SAFETY_ANALYSIS;
+  };
+  class GcRootEmptyFn {
+   public:
+    void MakeEmpty(GcRoot<mirror::Class>& item) const {
+      item = GcRoot<mirror::Class>();
+    }
+    bool IsEmpty(const GcRoot<mirror::Class>& item) const {
+      return item.IsNull();
+    }
+  };
+  // hash set which hashes class descriptor, and compares descriptors nad class loaders. Results
+  // should be compared for a matching Class descriptor and class loader.
+  typedef HashSet<GcRoot<mirror::Class>, GcRootEmptyFn, ClassDescriptorHashEquals,
+      ClassDescriptorHashEquals, TrackingAllocator<GcRoot<mirror::Class>, kAllocatorTagClassTable>>
+      ClassSet;
+
+  // TODO: shard lock to have one per class loader.
+  std::vector<ClassSet> classes_ GUARDED_BY(Locks::classlinker_classes_lock_);
+};
+
+}  // namespace art
+
+#endif  // ART_RUNTIME_CLASS_TABLE_H_