diff --git a/java/res/values/strings.xml b/java/res/values/strings.xml
index f24b433..a7d2bd9 100644
--- a/java/res/values/strings.xml
+++ b/java/res/values/strings.xml
@@ -428,6 +428,8 @@
     <string name="prefs_keypress_sound_volume_settings">Keypress sound volume</string>
     <!-- Title of the settings for reading an external dictionary file -->
     <string name="prefs_read_external_dictionary">Read external dictionary file</string>
+    <!-- Title of the settings for using only personalization dictionary -->
+    <string name="prefs_use_only_personalization_dictionary" translatable="false">Use only personalization dictionary</string>
     <!-- Message to show when there are no files to install as an external dictionary [CHAR LIMIT=100] -->
     <string name="read_external_dictionary_no_files_message">No dictionary files in the Downloads folder</string>
     <!-- Title of the dialog that selects a file to install as an external dictionary [CHAR LIMIT=50] -->
diff --git a/java/res/xml/prefs_for_debug.xml b/java/res/xml/prefs_for_debug.xml
index 8efd1c9..6958dda 100644
--- a/java/res/xml/prefs_for_debug.xml
+++ b/java/res/xml/prefs_for_debug.xml
@@ -51,6 +51,12 @@
             android:persistent="true"
             android:defaultValue="false" />
 
+    <CheckBoxPreference
+        android:defaultValue="false"
+        android:key="use_only_personalization_dictionary"
+        android:persistent="true"
+        android:title="@string/prefs_use_only_personalization_dictionary_for_debug" />
+
     <PreferenceScreen
         android:key="read_external_dictionary"
         android:title="@string/prefs_read_external_dictionary" />
diff --git a/java/src/com/android/inputmethod/latin/Suggest.java b/java/src/com/android/inputmethod/latin/Suggest.java
index 2879e2e..c2fdcb5 100644
--- a/java/src/com/android/inputmethod/latin/Suggest.java
+++ b/java/src/com/android/inputmethod/latin/Suggest.java
@@ -17,13 +17,16 @@
 package com.android.inputmethod.latin;
 
 import android.content.Context;
+import android.preference.PreferenceManager;
 import android.text.TextUtils;
+import android.util.Log;
 
 import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.keyboard.ProximityInfo;
 import com.android.inputmethod.latin.SuggestedWords.SuggestedWordInfo;
 import com.android.inputmethod.latin.personalization.PersonalizationPredictionDictionary;
 import com.android.inputmethod.latin.personalization.UserHistoryPredictionDictionary;
+import com.android.inputmethod.latin.settings.Settings;
 import com.android.inputmethod.latin.utils.AutoCorrectionUtils;
 import com.android.inputmethod.latin.utils.BoundedTreeSet;
 import com.android.inputmethod.latin.utils.CollectionUtils;
@@ -55,21 +58,22 @@
     // Close to -2**31
     private static final int SUPPRESS_SUGGEST_THRESHOLD = -2000000000;
 
+    public static final int MAX_SUGGESTIONS = 18;
+
     public interface SuggestInitializationListener {
         public void onUpdateMainDictionaryAvailability(boolean isMainDictionaryAvailable);
     }
 
     private static final boolean DBG = LatinImeLogger.sDBG;
 
-    private Dictionary mMainDictionary;
-    private ContactsBinaryDictionary mContactsDict;
     private final ConcurrentHashMap<String, Dictionary> mDictionaries =
             CollectionUtils.newConcurrentHashMap();
+    private HashSet<String> mOnlyDictionarySetForDebug = null;
+    private Dictionary mMainDictionary;
+    private ContactsBinaryDictionary mContactsDict;
     @UsedForTesting
     private boolean mIsCurrentlyWaitingForMainDictionary = false;
 
-    public static final int MAX_SUGGESTIONS = 18;
-
     private float mAutoCorrectionThreshold;
 
     // Locale used for upper- and title-casing words
@@ -79,6 +83,13 @@
             final SuggestInitializationListener listener) {
         initAsynchronously(context, locale, listener);
         mLocale = locale;
+        // initialize a debug flag for the personalization
+        if (Settings.readUseOnlyPersonalizationDictionaryForDebug(
+                PreferenceManager.getDefaultSharedPreferences(context))) {
+            mOnlyDictionarySetForDebug = new HashSet<String>();
+            mOnlyDictionarySetForDebug.add(Dictionary.TYPE_PERSONALIZATION);
+            mOnlyDictionarySetForDebug.add(Dictionary.TYPE_PERSONALIZATION_PREDICTION_IN_JAVA);
+        }
     }
 
     @UsedForTesting
@@ -87,7 +98,7 @@
                 false /* useFullEditDistance */, locale);
         mLocale = locale;
         mMainDictionary = mainDict;
-        addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_MAIN, mainDict);
+        addOrReplaceDictionaryInternal(Dictionary.TYPE_MAIN, mainDict);
     }
 
     private void initAsynchronously(final Context context, final Locale locale,
@@ -95,6 +106,14 @@
         resetMainDict(context, locale, listener);
     }
 
+    private void addOrReplaceDictionaryInternal(final String key, final Dictionary dict) {
+        if (mOnlyDictionarySetForDebug != null && mOnlyDictionarySetForDebug.contains(key)) {
+            Log.w(TAG, "Ignore add " + key + " dictionary for debug.");
+            return;
+        }
+        addOrReplaceDictionary(mDictionaries, key, dict);
+    }
+
     private static void addOrReplaceDictionary(
             final ConcurrentHashMap<String, Dictionary> dictionaries,
             final String key, final Dictionary dict) {
@@ -118,7 +137,7 @@
             public void run() {
                 final DictionaryCollection newMainDict =
                         DictionaryFactory.createMainDictionaryFromManager(context, locale);
-                addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_MAIN, newMainDict);
+                addOrReplaceDictionaryInternal(Dictionary.TYPE_MAIN, newMainDict);
                 mMainDictionary = newMainDict;
                 if (listener != null) {
                     listener.onUpdateMainDictionaryAvailability(hasMainDictionary());
@@ -156,7 +175,7 @@
      * before the main dictionary, if set. This refers to the system-managed user dictionary.
      */
     public void setUserDictionary(final UserBinaryDictionary userDictionary) {
-        addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_USER, userDictionary);
+        addOrReplaceDictionaryInternal(Dictionary.TYPE_USER, userDictionary);
     }
 
     /**
@@ -166,18 +185,18 @@
      */
     public void setContactsDictionary(final ContactsBinaryDictionary contactsDictionary) {
         mContactsDict = contactsDictionary;
-        addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_CONTACTS, contactsDictionary);
+        addOrReplaceDictionaryInternal(Dictionary.TYPE_CONTACTS, contactsDictionary);
     }
 
     public void setUserHistoryPredictionDictionary(
             final UserHistoryPredictionDictionary userHistoryPredictionDictionary) {
-        addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_USER_HISTORY,
+        addOrReplaceDictionaryInternal(Dictionary.TYPE_USER_HISTORY,
                 userHistoryPredictionDictionary);
     }
 
     public void setPersonalizationPredictionDictionary(
             final PersonalizationPredictionDictionary personalizationPredictionDictionary) {
-        addOrReplaceDictionary(mDictionaries, Dictionary.TYPE_PERSONALIZATION_PREDICTION_IN_JAVA,
+        addOrReplaceDictionaryInternal(Dictionary.TYPE_PERSONALIZATION_PREDICTION_IN_JAVA,
                 personalizationPredictionDictionary);
     }
 
diff --git a/java/src/com/android/inputmethod/latin/settings/DebugSettings.java b/java/src/com/android/inputmethod/latin/settings/DebugSettings.java
index e675f42..b1cd887 100644
--- a/java/src/com/android/inputmethod/latin/settings/DebugSettings.java
+++ b/java/src/com/android/inputmethod/latin/settings/DebugSettings.java
@@ -37,6 +37,8 @@
     public static final String PREF_FORCE_NON_DISTINCT_MULTITOUCH = "force_non_distinct_multitouch";
     public static final String PREF_USABILITY_STUDY_MODE = "usability_study_mode";
     public static final String PREF_STATISTICS_LOGGING = "enable_logging";
+    public static final String PREF_USE_ONLY_PERSONALIZATION_DICTIONARY_FOR_DEBUG =
+            "use_only_personalization_dictionary_for_debug";
     private static final String PREF_READ_EXTERNAL_DICTIONARY = "read_external_dictionary";
     private static final boolean SHOW_STATISTICS_LOGGING = false;
 
@@ -66,7 +68,7 @@
             }
         }
 
-        PreferenceScreen readExternalDictionary =
+        final PreferenceScreen readExternalDictionary =
                 (PreferenceScreen) findPreference(PREF_READ_EXTERNAL_DICTIONARY);
         if (null != readExternalDictionary) {
             readExternalDictionary.setOnPreferenceClickListener(
@@ -111,6 +113,8 @@
         } else if (key.equals(PREF_FORCE_NON_DISTINCT_MULTITOUCH)
                 || key.equals(KeyboardSwitcher.PREF_KEYBOARD_LAYOUT)) {
             mServiceNeedsRestart = true;
+        } else if (key.equals(PREF_USE_ONLY_PERSONALIZATION_DICTIONARY_FOR_DEBUG)) {
+            mServiceNeedsRestart = true;
         }
     }
 
diff --git a/java/src/com/android/inputmethod/latin/settings/Settings.java b/java/src/com/android/inputmethod/latin/settings/Settings.java
index 2631cd3..e6a0c07 100644
--- a/java/src/com/android/inputmethod/latin/settings/Settings.java
+++ b/java/src/com/android/inputmethod/latin/settings/Settings.java
@@ -324,4 +324,10 @@
     public static boolean isInternal(final SharedPreferences prefs) {
         return prefs.getBoolean(Settings.PREF_KEY_IS_INTERNAL, false);
     }
+
+    public static boolean readUseOnlyPersonalizationDictionaryForDebug(
+            final SharedPreferences prefs) {
+        return prefs.getBoolean(
+                DebugSettings.PREF_USE_ONLY_PERSONALIZATION_DICTIONARY_FOR_DEBUG, false);
+    }
 }