diff --git a/java/res/values/config.xml b/java/res/values/config.xml
index 6e941ba..5b5656d 100644
--- a/java/res/values/config.xml
+++ b/java/res/values/config.xml
@@ -25,4 +25,14 @@
     <integer name="config_preview_fadeout_anim_time">90</integer>
     <integer name="config_mini_keyboard_fadein_anim_time">0</integer>
     <integer name="config_mini_keyboard_fadeout_anim_time">100</integer>
+    <string-array name="auto_complete_threshold_values">
+        <!-- Off, When auto completing setting is Off, this value is not used. -->
+        <item></item>
+        <!-- Modest : Suggestion whose normalized score is greater than this value
+             will be subject to auto-completion. -->
+        <item>0.22</item>
+        <!-- Aggressive : Suggestion whose normalized score is greater than this value
+             will be subject to auto-completion. -->
+        <item>0</item>
+    </string-array>
 </resources>
diff --git a/java/res/values/strings.xml b/java/res/values/strings.xml
index a4ebe46..94fe76d 100644
--- a/java/res/values/strings.xml
+++ b/java/res/values/strings.xml
@@ -86,11 +86,6 @@
     <!-- Description for show suggestions -->
     <string name="show_suggestions_summary">Display suggested words while typing</string>
     
-    <!-- Option to enable auto completion -->
-    <string name="auto_complete">Auto-complete</string>
-    <!-- Description for auto completion -->
-    <string name="auto_complete_summary">Spacebar and punctuation automatically insert highlighted word</string>
-    
     <!-- Option to show/hide the settings key -->
     <string name="prefs_settings_key">Show settings key</string>
     <!-- Array of the settings key mode values -->
@@ -112,6 +107,31 @@
         <item>@string/settings_key_mode_always_hide_name</item>
     </string-array>
 
+    <!-- Option to decide the auto completion threshold score -->
+    <!-- Option to enable auto completion -->
+    <string name="auto_complete">Auto-complete</string>
+    <!-- Description for auto completion -->
+    <string name="auto_complete_summary">Spacebar and punctuation automatically insert highlighted word</string>
+    <string name="auto_completion_threshold_mode_value_off" translatable="false">0</string>
+    <string name="auto_completion_threshold_mode_value_modest" translatable="false">1</string>
+    <string name="auto_completion_threshold_mode_value_aggeressive" translatable="false">2</string>
+    <string-array name="auto_completion_threshold_mode_values" translatable="false">
+      <item>@string/auto_completion_threshold_mode_value_off</item>
+      <item>@string/auto_completion_threshold_mode_value_modest</item>
+      <item>@string/auto_completion_threshold_mode_value_aggeressive</item>
+    </string-array>
+    <!-- Option to disable auto completion. -->
+    <string name="auto_completion_threshold_mode_off">Off</string>
+    <!-- Option to use modest auto completion. -->
+    <string name="auto_completion_threshold_mode_modest">Modest</string>
+    <!-- Option to use aggressive auto completion. -->
+    <string name="auto_completion_threshold_mode_aggeressive">Aggressive</string>
+    <string-array name="auto_completion_threshold_modes">
+      <item>@string/auto_completion_threshold_mode_off</item>
+      <item>@string/auto_completion_threshold_mode_modest</item>
+      <item>@string/auto_completion_threshold_mode_aggeressive</item>
+    </string-array>
+
     <!-- Option to enable bigram completion -->
     <string name="bigram_suggestion">Bigram Suggestions</string>
     <!-- Description for auto completion -->
diff --git a/java/res/xml/prefs.xml b/java/res/xml/prefs.xml
index 8a97109..e7a3945 100644
--- a/java/res/xml/prefs.xml
+++ b/java/res/xml/prefs.xml
@@ -97,13 +97,14 @@
             android:defaultValue="true"
             />
 
-        <CheckBoxPreference
-            android:key="auto_complete"
+        <ListPreference
+            android:key="auto_completion_threshold"
             android:title="@string/auto_complete"
             android:summary="@string/auto_complete_summary"
-            android:persistent="true" 
-            android:defaultValue="@bool/enable_autocorrect"
-            android:dependency="show_suggestions"
+            android:persistent="true"
+            android:entryValues="@array/auto_completion_threshold_mode_values"
+            android:entries="@array/auto_completion_threshold_modes"
+            android:defaultValue="@string/auto_completion_threshold_mode_value_modest"
             />
 
         <CheckBoxPreference
@@ -112,7 +113,6 @@
             android:summary="@string/bigram_suggestion_summary"
             android:persistent="true"
             android:defaultValue="true"
-            android:dependency="auto_complete"
             />
     </PreferenceCategory>            
 
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index b41c2aa..d0c8af5 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -68,6 +68,7 @@
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -94,7 +95,7 @@
     private static final String PREF_AUTO_CAP = "auto_cap";
     private static final String PREF_QUICK_FIXES = "quick_fixes";
     private static final String PREF_SHOW_SUGGESTIONS = "show_suggestions";
-    private static final String PREF_AUTO_COMPLETE = "auto_complete";
+    private static final String PREF_AUTO_COMPLETION_THRESHOLD = "auto_completion_threshold";
     private static final String PREF_BIGRAM_SUGGESTIONS = "bigram_suggestion";
     private static final String PREF_VOICE_MODE = "voice_mode";
 
@@ -445,6 +446,7 @@
 
         int[] dictionaries = getDictionary(orig);
         mSuggest = new Suggest(this, dictionaries);
+        loadAndSetAutoCompletionThreshold(sp);
         updateAutoTextEnabled(saveLocale);
         if (mUserDictionary != null) mUserDictionary.close();
         mUserDictionary = new UserDictionary(this, mInputLocale);
@@ -2469,6 +2471,9 @@
         mLocaleSupportedForVoiceInput = voiceInputSupportedLocales.contains(mInputLocale);
 
         mShowSuggestions = sp.getBoolean(PREF_SHOW_SUGGESTIONS, true);
+        mAutoCorrectEnabled = mShowSuggestions && isAutoCorrectEnabled(sp);
+        mBigramSuggestionEnabled = mAutoCorrectEnabled && isBigramSuggestionEnabled(sp);
+        loadAndSetAutoCompletionThreshold(sp);
 
         if (VOICE_INSTALLED) {
             final String voiceMode = sp.getString(PREF_VOICE_MODE,
@@ -2483,14 +2488,61 @@
             mEnableVoice = enableVoice;
             mVoiceOnPrimary = voiceOnPrimary;
         }
-        mAutoCorrectEnabled = sp.getBoolean(PREF_AUTO_COMPLETE,
-                mResources.getBoolean(R.bool.enable_autocorrect)) & mShowSuggestions;
-        mBigramSuggestionEnabled = sp.getBoolean(PREF_BIGRAM_SUGGESTIONS, true) & mShowSuggestions;
         updateCorrectionMode();
         updateAutoTextEnabled(mResources.getConfiguration().locale);
         mLanguageSwitcher.loadLocales(sp);
     }
 
+    /**
+     *  load Auto completion threshold from SharedPreferences,
+     *  and modify mSuggest's threshold.
+     */
+    private void loadAndSetAutoCompletionThreshold(SharedPreferences sp) {
+        // When mSuggest is not initialized, cannnot modify mSuggest's threshold.
+        if (mSuggest == null) return;
+        // When auto completion setting is turned off, the threshold is ignored.
+        if (!isAutoCorrectEnabled(sp)) return;
+
+        final String currentAutoCompletionSetting = sp.getString(PREF_AUTO_COMPLETION_THRESHOLD,
+                mResources.getString(R.string.auto_completion_threshold_mode_value_modest));
+        final String[] autoCompletionThresholdValues = mResources.getStringArray(
+                R.array.auto_complete_threshold_values);
+        // When autoCompletionThreshold is greater than 1.0,
+        // auto completion is virtually turned off.
+        double autoCompletionThreshold = Double.MAX_VALUE;
+        try {
+            final int arrayIndex = Integer.valueOf(currentAutoCompletionSetting);
+            if (arrayIndex >= 0 && arrayIndex < autoCompletionThresholdValues.length) {
+                autoCompletionThreshold = Double.parseDouble(
+                        autoCompletionThresholdValues[arrayIndex]);
+            }
+        } catch (NumberFormatException e) {
+            // Whenever the threshold settings are correct,
+            // never come here.
+            autoCompletionThreshold = Double.MAX_VALUE;
+            Log.w(TAG, "Cannot load auto completion threshold setting."
+                    + " currentAutoCompletionSetting: " + currentAutoCompletionSetting
+                    + ", autoCompletionThresholdValues: "
+                    + Arrays.toString(autoCompletionThresholdValues));
+        }
+        // TODO: This should be refactored :
+        //           setAutoCompleteThreshold should be called outside of this method.
+        mSuggest.setAutoCompleteThreshold(autoCompletionThreshold);
+    }
+
+    private boolean isAutoCorrectEnabled(SharedPreferences sp) {
+        final String currentAutoCompletionSetting = sp.getString(PREF_AUTO_COMPLETION_THRESHOLD,
+                mResources.getString(R.string.auto_completion_threshold_mode_value_modest));
+        final String autoCompletionOff = mResources.getString(
+                R.string.auto_completion_threshold_mode_value_off);
+        return !currentAutoCompletionSetting.equals(autoCompletionOff);
+    }
+
+    private boolean isBigramSuggestionEnabled(SharedPreferences sp) {
+       // TODO: Define default value instead of 'true'.
+       return sp.getBoolean(PREF_BIGRAM_SUGGESTIONS, true);
+    }
+
     private void initSuggestPuncList() {
         mSuggestPuncList = new ArrayList<CharSequence>();
         mSuggestPuncs = mResources.getString(R.string.suggested_punctuations);
diff --git a/java/src/com/android/inputmethod/latin/LatinIMESettings.java b/java/src/com/android/inputmethod/latin/LatinIMESettings.java
index ffff33d..99d8a62 100644
--- a/java/src/com/android/inputmethod/latin/LatinIMESettings.java
+++ b/java/src/com/android/inputmethod/latin/LatinIMESettings.java
@@ -43,6 +43,9 @@
     private static final String QUICK_FIXES_KEY = "quick_fixes";
     private static final String PREDICTION_SETTINGS_KEY = "prediction_settings";
     private static final String VOICE_SETTINGS_KEY = "voice_mode";
+    private static final String PREF_SHOW_SUGGESTIONS = "show_suggestions";
+    private static final String PREF_AUTO_COMPLETION_THRESHOLD = "auto_completion_threshold";
+    private static final String PREF_BIGRAM_SUGGESTIONS = "bigram_suggestion";
     /* package */ static final String PREF_SETTINGS_KEY = "settings_key";
 
     private static final String TAG = "LatinIMESettings";
@@ -53,6 +56,9 @@
     private CheckBoxPreference mQuickFixes;
     private ListPreference mVoicePreference;
     private ListPreference mSettingsKeyPreference;
+    private CheckBoxPreference mShowSuggestions;
+    private ListPreference mAutoCompletionThreshold;
+    private CheckBoxPreference mBigramSuggestion;
     private boolean mVoiceOn;
 
     private VoiceInputLogger mLogger;
@@ -60,6 +66,18 @@
     private boolean mOkClicked = false;
     private String mVoiceModeOff;
 
+    private void ensureConsistencyOfAutoCompletionSettings() {
+        if (mShowSuggestions.isChecked()) {
+            mAutoCompletionThreshold.setEnabled(true);
+            final String autoCompletionOff = getResources().getString(
+                    R.string.auto_completion_threshold_mode_value_off);
+            final String currentSetting = mAutoCompletionThreshold.getValue();
+            mBigramSuggestion.setEnabled(!currentSetting.equals(autoCompletionOff));
+        } else {
+            mAutoCompletionThreshold.setEnabled(false);
+            mBigramSuggestion.setEnabled(false);
+        }
+    }
     @Override
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);
@@ -73,6 +91,11 @@
         mVoiceModeOff = getString(R.string.voice_mode_off);
         mVoiceOn = !(prefs.getString(VOICE_SETTINGS_KEY, mVoiceModeOff).equals(mVoiceModeOff));
         mLogger = VoiceInputLogger.getLogger(this);
+
+        mShowSuggestions = (CheckBoxPreference) findPreference(PREF_SHOW_SUGGESTIONS);
+        mAutoCompletionThreshold = (ListPreference) findPreference(PREF_AUTO_COMPLETION_THRESHOLD);
+        mBigramSuggestion = (CheckBoxPreference) findPreference(PREF_BIGRAM_SUGGESTIONS);
+        ensureConsistencyOfAutoCompletionSettings();
     }
 
     @Override
@@ -108,6 +131,7 @@
                 showVoiceConfirmation();
             }
         }
+        ensureConsistencyOfAutoCompletionSettings();
         mVoiceOn = !(prefs.getString(VOICE_SETTINGS_KEY, mVoiceModeOff).equals(mVoiceModeOff));
         updateVoiceModeSummary();
         updateSettingsKeySummary();
diff --git a/java/src/com/android/inputmethod/latin/LatinIMEUtil.java b/java/src/com/android/inputmethod/latin/LatinIMEUtil.java
index 85ecaee..d936390 100644
--- a/java/src/com/android/inputmethod/latin/LatinIMEUtil.java
+++ b/java/src/com/android/inputmethod/latin/LatinIMEUtil.java
@@ -168,4 +168,58 @@
             mLength = 0;
         }
     }
+
+    public static int editDistance(CharSequence s, CharSequence t) {
+        if (s == null || t == null) {
+            throw new IllegalArgumentException("editDistance: Arguments should not be null.");
+        }
+        final int sl = s.length();
+        final int tl = t.length();
+        int[][] dp = new int [sl + 1][tl + 1];
+        for (int i = 0; i <= sl; i++) {
+            dp[i][0] = i;
+        }
+        for (int j = 0; j <= tl; j++) {
+            dp[0][j] = j;
+        }
+        for (int i = 0; i < sl; ++i) {
+            for (int j = 0; j < tl; ++j) {
+                if (s.charAt(i) == t.charAt(j)) {
+                    dp[i + 1][j + 1] = dp[i][j];
+                } else {
+                    dp[i + 1][j + 1] = 1 + Math.min(dp[i][j],
+                            Math.min(dp[i + 1][j], dp[i][j + 1]));
+                }
+            }
+        }
+        return dp[sl][tl];
+    }
+
+    // In dictionary.cpp, getSuggestion() method,
+    // suggestion scores are computed using the below formula.
+    // original score (called 'frequency')
+    //  := pow(mTypedLetterMultiplier (this is defined 2),
+    //         (the number of matched characters between typed word and suggested word))
+    //     * (individual word's score which defined in the unigram dictionary,
+    //         and this score is defined in range [0, 255].)
+    //     * (when before.length() == after.length(),
+    //         mFullWordMultiplier (this is defined 2))
+    // So, maximum original score is pow(2, before.length()) * 255 * 2
+    // So, we can normalize original score by dividing this value.
+    private static final int MAX_INITIAL_SCORE = 255;
+    private static final int TYPED_LETTER_MULTIPLIER = 2;
+    private static final int FULL_WORD_MULTIPLYER = 2;
+    public static double calcNormalizedScore(CharSequence before, CharSequence after, int score) {
+        final int beforeLength = before.length();
+        final int afterLength = after.length();
+        final int distance = editDistance(before, after);
+        final double maximumScore = MAX_INITIAL_SCORE
+                * Math.pow(TYPED_LETTER_MULTIPLIER, beforeLength)
+                * FULL_WORD_MULTIPLYER;
+        // add a weight based on edit distance.
+        // distance <= max(afterLength, beforeLength) == afterLength,
+        // so, 0 <= distance / afterLength <= 1
+        final double weight = 1.0 - (double) distance / afterLength;
+        return (score / maximumScore) * weight;
+    }
 }
diff --git a/java/src/com/android/inputmethod/latin/Suggest.java b/java/src/com/android/inputmethod/latin/Suggest.java
index 3b89894..0178233 100755
--- a/java/src/com/android/inputmethod/latin/Suggest.java
+++ b/java/src/com/android/inputmethod/latin/Suggest.java
@@ -81,6 +81,7 @@
 
     private boolean mAutoTextEnabled;
 
+    private double mAutoCompleteThreshold;
     private int[] mPriorities = new int[mPrefMaxSuggestions];
     private int[] mBigramPriorities = new int[PREF_MAX_BIGRAMS];
 
@@ -163,6 +164,10 @@
         mUserBigramDictionary = userBigramDictionary;
     }
 
+    public void setAutoCompleteThreshold(double threshold) {
+        mAutoCompleteThreshold = threshold;
+    }
+
     /**
      * Number of suggestions to generate from the input key sequence. This has
      * to be a number between 1 and 100 (inclusive).
@@ -301,8 +306,14 @@
             }
             mMainDict.getWords(wordComposer, this, mNextLettersFrequencies);
             if ((mCorrectionMode == CORRECTION_FULL || mCorrectionMode == CORRECTION_FULL_BIGRAM)
-                    && mSuggestions.size() > 0) {
-                mHaveCorrection = true;
+                    && mSuggestions.size() > 0 && mPriorities.length > 0) {
+                // TODO: when the normalized score of the first suggestion is nearly equals to
+                //       the normalized score of the second suggestion, behave less aggressive.
+                final double normalizedScore = LatinIMEUtil.calcNormalizedScore(
+                        mOriginalWord, mSuggestions.get(0), mPriorities[0]);
+                if (normalizedScore >= mAutoCompleteThreshold) {
+                    mHaveCorrection = true;
+                }
             }
         }
         if (mOriginalWord != null) {