diff --git a/res/values/strings.xml b/res/values/strings.xml
index f950ad2..c7c6bf9 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -675,6 +675,9 @@
       and return to the editor [CHAR LIMIT=30] -->
     <string name="cancel_confirmation_dialog_keep_editing_button">Cancel</string>
 
+    <!-- Contents of the alert dialog when the user hits the Cancel button in the customize screen [CHAR LIMIT=128] -->
+    <string name="leave_customize_confirmation_dialog_message">Discard customizations?</string>
+
     <!-- Description of a call log entry, made of a call type and a date -->
     <string name="call_type_and_date">
         <xliff:g id="call_type" example="Friends">%1$s</xliff:g>  <xliff:g id="call_short_date" example="Friends">%2$s</xliff:g>
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 9ff882d..33fa11e 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -486,11 +486,6 @@
         <item name="android:overScrollMode">always</item>
     </style>
 
-    <style name="ContactListFilterTheme" parent="@android:Theme.Holo.Light">
-        <item name="android:listViewStyle">@style/ListViewStyle</item>
-        <item name="android:actionButtonStyle">@style/FilterActionButtonStyle</item>
-    </style>
-
     <!-- Adding padding to action button doesn't move it to left, we increase the button width to
      make margin between the button and screen edge 16dp -->
     <style name="FilterActionButtonStyle" parent="@android:Widget.ActionButton">
diff --git a/src/com/android/contacts/common/list/AccountFilterActivity.java b/src/com/android/contacts/common/list/AccountFilterActivity.java
index bed6977..3908d18 100644
--- a/src/com/android/contacts/common/list/AccountFilterActivity.java
+++ b/src/com/android/contacts/common/list/AccountFilterActivity.java
@@ -90,8 +90,9 @@
         if (filter.filterType == ContactListFilter.FILTER_TYPE_CUSTOM) {
             mCustomFilterView = listFilterView;
             mIsCustomFilterViewSelected = listFilterView.isChecked();
-            final Intent intent = new Intent(this,
-                    CustomContactListFilterActivity.class);
+            final Intent intent = new Intent(this, CustomContactListFilterActivity.class)
+                    .putExtra(CustomContactListFilterActivity.EXTRA_CURRENT_LIST_FILTER_TYPE,
+                            mCurrentFilterType);
             listFilterView.setActivated(true);
             // Switching activity has the highest priority. So when we open another activity, the
             // announcement that indicates an account is checked will be interrupted. This is the
diff --git a/src/com/android/contacts/common/list/CustomContactListFilterActivity.java b/src/com/android/contacts/common/list/CustomContactListFilterActivity.java
index 04337b8..74e8f84 100644
--- a/src/com/android/contacts/common/list/CustomContactListFilterActivity.java
+++ b/src/com/android/contacts/common/list/CustomContactListFilterActivity.java
@@ -19,6 +19,8 @@
 import android.app.ActionBar;
 import android.app.Activity;
 import android.app.AlertDialog;
+import android.app.Dialog;
+import android.app.DialogFragment;
 import android.app.LoaderManager.LoaderCallbacks;
 import android.app.ProgressDialog;
 import android.content.AsyncTaskLoader;
@@ -30,14 +32,12 @@
 import android.content.Intent;
 import android.content.Loader;
 import android.content.OperationApplicationException;
-import android.content.SharedPreferences;
 import android.database.Cursor;
 import android.graphics.Color;
 import android.graphics.drawable.ColorDrawable;
 import android.net.Uri;
 import android.os.Bundle;
 import android.os.RemoteException;
-import android.preference.PreferenceManager;
 import android.provider.ContactsContract;
 import android.provider.ContactsContract.Groups;
 import android.provider.ContactsContract.Settings;
@@ -81,13 +81,13 @@
         LoaderCallbacks<CustomContactListFilterActivity.AccountSet> {
     private static final String TAG = "CustomContactListFilterActivity";
 
+    public static final String EXTRA_CURRENT_LIST_FILTER_TYPE = "currentListFilterType";
+
     private static final int ACCOUNT_SET_LOADER_ID = 1;
 
     private ExpandableListView mList;
     private DisplayAdapter mAdapter;
 
-    private SharedPreferences mPrefs;
-
     @Override
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);
@@ -111,7 +111,6 @@
             }
         });
 
-        mPrefs = PreferenceManager.getDefaultSharedPreferences(this);
         mAdapter = new DisplayAdapter(this);
 
         mList.setOnCreateContextMenuListener(this);
@@ -837,6 +836,20 @@
         }
     }
 
+    private boolean hasUnsavedChanges() {
+        if (mAdapter == null || mAdapter.mAccounts == null) {
+            return false;
+        }
+        if (getCurrentListFilterType() != ContactListFilter.FILTER_TYPE_CUSTOM) {
+            return true;
+        }
+        final ArrayList<ContentProviderOperation> diff = mAdapter.mAccounts.buildDiff();
+        if (diff.isEmpty()) {
+            return false;
+        }
+        return true;
+    }
+
     @SuppressWarnings("unchecked")
     private void doSaveAction() {
         if (mAdapter == null || mAdapter.mAccounts == null) {
@@ -933,9 +946,7 @@
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
             case android.R.id.home:
-                // Pretend cancel.
-                setResult(Activity.RESULT_CANCELED);
-                finish();
+                confirmFinish();
                 return true;
             case R.id.menu_save:
                 this.doSaveAction();
@@ -945,4 +956,47 @@
         }
         return super.onOptionsItemSelected(item);
     }
+
+    @Override
+    public void onBackPressed() {
+        confirmFinish();
+    }
+
+    private void confirmFinish() {
+        // Prompt the user whether they want to discard there customizations unless
+        // nothing will be changed.
+        if (hasUnsavedChanges()) {
+            new ConfirmNavigationDialogFragment().show(getFragmentManager(),
+                    "ConfirmNavigationDialog");
+        } else {
+            setResult(RESULT_CANCELED);
+            finish();
+        }
+    }
+
+    private int getCurrentListFilterType() {
+        return getIntent().getIntExtra(EXTRA_CURRENT_LIST_FILTER_TYPE,
+                ContactListFilter.FILTER_TYPE_ALL_ACCOUNTS);
+    }
+
+    public static class ConfirmNavigationDialogFragment
+            extends DialogFragment implements DialogInterface.OnClickListener {
+
+        @Override
+        public Dialog onCreateDialog(Bundle savedInstanceState) {
+            return new AlertDialog.Builder(getActivity(), getTheme())
+                    .setMessage(R.string.leave_customize_confirmation_dialog_message)
+                    .setNegativeButton(android.R.string.no, null)
+                    .setPositiveButton(android.R.string.yes, this)
+                    .create();
+        }
+
+        @Override
+        public void onClick(DialogInterface dialogInterface, int i) {
+            if (i == DialogInterface.BUTTON_POSITIVE) {
+                getActivity().setResult(RESULT_CANCELED);
+                getActivity().finish();
+            }
+        }
+    }
 }