diff --git a/README.md b/README.md
index 8acc65a..0258191 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,8 @@ PHP 5.3+ and HHVM. Inspired by underscore.string.js.
     * [htmlDecode](#htmldecode)
     * [htmlEncode](#htmlencode)
     * [humanize](#humanize)
+    * [indexOf](#indexof)
+    * [indexOfLast](#indexoflast)
     * [insert](#insert)
     * [isAlpha](#isalpha)
     * [isAlphanumeric](#isalphanumeric)
@@ -475,6 +477,34 @@ S::create('author_id')->humanize();
 S::humanize('author_id');  // 'Author'
 ```
 
+#### indexOf
+
+$stringy->indexOf(string $substr [, $offset = 0 ]);
+
+S::indexOf(string $str , string $substr [, $offset = 0 [, $encoding = null ]])
+
+Returns the offset/index of the first occurrence of $substr in the string.
+In case $substr is not a substring of the string, returns false.
+
+```php
+S::create('string', 'UTF-8')->indexOf('ing');
+S::indexOf('string', 'ing', 0, 'UTF-8');  // 3
+```
+
+#### indexOfLast
+
+$stringy->indexOfLast(string $substr [, $offset = 0 ]);
+
+S::indexOfLast(string $str , string $substr [, $offset = 0 [, $encoding = null ]])
+
+Returns the offset/index of the last occurrence of $substr in the string.
+In case $substr is not a substring of the string, returns false.
+
+```php
+S::create('string', 'UTF-8')->indexOfLast('ing');
+S::indexOfLast('string string', 'ing', 0, 'UTF-8');  // 10
+```
+
 #### insert
 
 $stringy->insert(int $index, string $substring)
diff --git a/src/StaticStringy.php b/src/StaticStringy.php
index 0462395..d9ac76a 100644
--- a/src/StaticStringy.php
+++ b/src/StaticStringy.php
@@ -421,6 +421,34 @@ class StaticStringy
             ->containsAll($needles, $caseSensitive);
     }
 
+    /**
+     * Returns the offset/index of the first occurance of $substr in the string.
+     * In case $substr is not a substring of the string, returns false.
+     *
+     * @param string $str         The haystack to search through
+     * @param string $substr substring
+     * @param int $offset
+     * @return int|bool
+     */
+    public static function indexOf($str, $substr, $offset = 0, $encoding = null)
+    {
+        return Stringy::create($str, $encoding)->indexOf($substr, $offset);
+    }
+
+    /**
+     * Returns the offset/index of the last occurance of $substr in the string.
+     * In case $substr is not a substring of the string, returns false.
+     *
+     * @param string $str         The haystack to search through
+     * @param string $substr substring
+     * @param int $offset
+     * @return int|bool
+     */
+    public static function indexOfLast($str, $substr, $offset = 0, $encoding = null)
+    {
+        return Stringy::create($str, $encoding)->indexOfLast($substr, $offset);
+    }
+
     /**
      * Surrounds a string with the given substring.
      *
diff --git a/src/Stringy.php b/src/Stringy.php
index 23e9cd9..8a03bf4 100644
--- a/src/Stringy.php
+++ b/src/Stringy.php
@@ -894,6 +894,32 @@ class Stringy implements \Countable, \IteratorAggregate, \ArrayAccess
         return true;
     }
 
+    /**
+     * Returns the offset/index of the first occurrence of $substr in the string.
+     * In case $substr is not a substring of the string, returns false.
+     *
+     * @param string $substr substring
+     * @param int $offset
+     * @return int|bool
+     */
+    public function indexOf($substr, $offset = 0)
+    {
+        return mb_strpos($this->str, (string)$substr, (int)$offset, $this->encoding);
+    }
+
+    /**
+     * Returns the offset/index of the last occurrence of $substr in the string.
+     * In case $substr is not a substring of the string, returns false.
+     *
+     * @param string $substr substring
+     * @param int $offset
+     * @return int|bool
+     */
+    public function indexOfLast($substr, $offset = 0)
+    {
+        return mb_strrpos($this->str, (string)$substr, (int)$offset, $this->encoding);
+    }
+
     /**
      * Surrounds $str with the given substring.
      *
diff --git a/tests/CommonTest.php b/tests/CommonTest.php
index aa08026..de1d523 100644
--- a/tests/CommonTest.php
+++ b/tests/CommonTest.php
@@ -14,6 +14,26 @@ abstract class CommonTest extends PHPUnit_Framework_TestCase
         $this->assertInstanceOf('Stringy\Stringy', $actual);
     }
 
+    public function indexOfProvider()
+    {
+        return array(
+            array(2, 'This is the string', 'is'),
+            array(2, 'This is the string', 'is', 0, 'UTF-8'),
+            array(false, 'This is the string', 'not-found', 0, 'UTF-8'),
+            array(32, 'This is the string... and there is another thing', 'is', 10, 'UTF-8'),
+        );
+    }
+
+    public function indexOfLastProvider()
+    {
+        return array(
+            array(5, 'This is the string', 'is'),
+            array(5, 'This is the string', 'is', 0, 'UTF-8'),
+            array(false, 'This is the string', 'not-found', 0, 'UTF-8'),
+            array(32, 'This is the string... and there is another thing', 'is', 0, 'UTF-8'),
+        );
+    }
+
     public function charsProvider()
     {
         return array(
diff --git a/tests/StaticStringyTest.php b/tests/StaticStringyTest.php
index f029bb2..c093219 100644
--- a/tests/StaticStringyTest.php
+++ b/tests/StaticStringyTest.php
@@ -6,6 +6,24 @@ use Stringy\StaticStringy as S;
 
 class StaticStringyTestCase extends CommonTest
 {
+	/**
+     * @dataProvider indexOfProvider()
+     */
+    public function testIndexOf($expected, $str, $subStr, $offset = 0, $encoding = null)
+    {
+        $result = S::indexOf($str, $subStr, $offset, $encoding);
+        $this->assertEquals($expected, $result);
+    }
+
+    /**
+     * @dataProvider indexOfLastProvider()
+     */
+    public function testIndexOfLast($expected, $str, $subStr, $offset = 0, $encoding = null)
+    {
+        $result = S::indexOfLast($str, $subStr, $offset, $encoding);
+        $this->assertEquals($expected, $result);
+    }
+
     /**
      * @dataProvider charsProvider()
      */
diff --git a/tests/StringyTest.php b/tests/StringyTest.php
index 4bba637..a9a65b3 100644
--- a/tests/StringyTest.php
+++ b/tests/StringyTest.php
@@ -153,6 +153,24 @@ class StringyTestCase extends CommonTest
         unset($stringy[1]);
     }
 
+    /**
+     * @dataProvider indexOfProvider()
+     */
+    public function testIndexOf($expected, $str, $subStr, $offset = 0, $encoding = null)
+    {
+        $result = S::create($str, $encoding)->indexOf($subStr, $offset);
+        $this->assertEquals($expected, $result);
+    }
+
+    /**
+     * @dataProvider indexOfLastProvider()
+     */
+    public function testIndexOfLast($expected, $str, $subStr, $offset = 0, $encoding = null)
+    {
+        $result = S::create($str, $encoding)->indexOfLast($subStr, $offset);
+        $this->assertEquals($expected, $result);
+    }
+
     /**
      * @dataProvider charsProvider()
      */