diff --git a/README.md b/README.md
index a72e75a..5eeb6e2 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,7 @@ Bunch of useful filters for AngularJS *(with no external dependencies!)*
   - [where](#where)
   - [xor](#xor)
 - [String](#string)
+  - [camelize](#camelize)
   - [endsWith](#endswith)
   - [latinize](#latinize)
   - [repeat](#repeat)
@@ -66,6 +67,7 @@ Bunch of useful filters for AngularJS *(with no external dependencies!)*
   - [rtrim](#rtrim)
   - [truncate](#truncate)
   - [ucfirst](#ucfirst)
+  - [underscore](#underscore)
   - [uriEncode](#uriencode)
   - [uriComponentEncode](#uricomponentencode)
   - [wrap](#wrap)
@@ -983,13 +985,18 @@ $scope.double = function(i) {
 ###ucfirst
 
 ucfirstFilter get string as parameter and return it capitalized
+usage: ```string | ucfirst: [lettersOnly:boolean|optional]```<br/>
+**aliases:** titleize
+
 
 ```html
 <p> {{ 'foo bar baz' | ucfirst }}</p>
+<p> {{ 'foo bar baz' | ucfirst: true }}</p>
 
 <!--
 result:
 Foo Bar Baz
+FooBarBaz
 -->
 ```
 
@@ -1083,7 +1090,7 @@ get string with {n} and replace match with enumeration values
 ```
 
 ### phoneUS
-Format a string or a number into a us-style phone number  
+Format a string or a number into a us-style phone number
 ```html
 <p>{{ 1234567890 | phoneUS }}</p>
 
@@ -1200,6 +1207,44 @@ Return an array of matched element in a string<br/>
 ['15', '12', '2003']
 ```
 
+###underscore
+
+Converts a string to underscore(snake_case)
+**Usage:** ```string | underscore```<br/>
+**aliases:** snakeCase
+
+```html
+<p>{{ 'fooBarBaz' | underscore }}</p>
+<p>{{ 'ANUPPERCASEDWORD' | underscore }}</p>
+
+<!--
+result:
+foo_bar_baz
+a_n_u_p_p_e_r_c_a_s_e_d_w_o_r_d
+-->
+```
+
+###camelize
+
+Converts a string to camelCase<br/>
+**Usage:** ```string | camelize```<br/>
+**aliases:** camelCase
+
+```html
+<p>{{ 'a_simple_word' | camelize }}</p>
+<p>{{ 'ANUPPERCASEDWORD' | camelize }}</p>
+<p>{{ 'angular-js' | camelize }}</p>
+<p>{{ 'a sentence' | camelize }}</p>
+
+<!--
+result:
+aSimpleWord
+angularJs
+anuppercasedword
+aSentence
+-->
+```
+
 ## Math
 
 ###max
diff --git a/src/_filter/string/camelize.js b/src/_filter/string/camelize.js
new file mode 100644
index 0000000..364b104
--- /dev/null
+++ b/src/_filter/string/camelize.js
@@ -0,0 +1,29 @@
+/**
+ * @ngdoc filter
+ * @name camelize
+ * @kind function
+ *
+ * @description
+ * Converts a string to camelCase
+ */
+angular.module('a8m.camelize', [])
+  .filter({
+    camelize: camelizeFilter,
+    camelCase: camelizeFilter
+  });
+
+function camelizeFilter() {
+  return function(input) {
+    if (!isString(input)) return input;
+
+    return input.toLowerCase()
+      .split(/[-_\s]+/g)
+      .filter(function(value) {
+        return value !== '';
+      })
+      .map(function(value, index) {
+        return index === 0 ? value : value.slice(0, 1).toUpperCase() + value.slice(1);
+      })
+      .join('');
+  }
+}
diff --git a/src/_filter/string/ucfirst.js b/src/_filter/string/ucfirst.js
index d81fa61..e6d7be9 100644
--- a/src/_filter/string/ucfirst.js
+++ b/src/_filter/string/ucfirst.js
@@ -13,14 +13,25 @@ angular.module('a8m.ucfirst', [])
   });
 
 function ucfirstFilter() {
-  return function (input) {
-    return isString(input)
-      ? input
+  return function (input, lettersOnly) {
+    if (!isString(input)) {
+      return input;
+    }
+
+    var delimiter = ' ';
+    var newWord = input;
+
+    if (!!lettersOnly) {
+      delimiter = '';
+      newWord = input.replace(/[^a-zA-Z ]/g, '');
+    }
+
+    return newWord
+      .toLowerCase()
       .split(' ')
       .map(function (ch) {
         return ch.charAt(0).toUpperCase() + ch.substring(1);
       })
-      .join(' ')
-      : input;
+      .join(delimiter);
   }
 }
diff --git a/src/_filter/string/underscore.js b/src/_filter/string/underscore.js
new file mode 100644
index 0000000..21253ba
--- /dev/null
+++ b/src/_filter/string/underscore.js
@@ -0,0 +1,22 @@
+/**
+ * @ngdoc filter
+ * @name underscore
+ * @kind function
+ *
+ * @description
+ * Converts a string to underscore
+ */
+angular.module('a8m.underscore', [])
+  .filter({
+    underscore: underscoreFilter,
+    snakeCase: underscoreFilter
+  });
+
+function underscoreFilter() {
+  return function(input) {
+    if (!isString(input)) return input;
+
+    return input.replace(/\W/g, '').replace(
+      /[A-Z]/g, function(value, index) { return index === 0 ? value.toLowerCase() : '_' + value.toLowerCase() });
+  }
+}
diff --git a/src/filters.js b/src/filters.js
index f757f8d..8052d39 100644
--- a/src/filters.js
+++ b/src/filters.js
@@ -25,6 +25,8 @@ angular.module('angular.filter', [
   'a8m.test',
   'a8m.match',
   'a8m.split',
+  'a8m.underscore',
+  'a8m.camelize',
 
   'a8m.to-array',
   'a8m.concat',
diff --git a/test/spec/filter/string/camelize.js b/test/spec/filter/string/camelize.js
new file mode 100644
index 0000000..b3afde1
--- /dev/null
+++ b/test/spec/filter/string/camelize.js
@@ -0,0 +1,31 @@
+'use strict';
+
+describe('camelizeFilter', function () {
+
+  var filter;
+
+  beforeEach(module('a8m.camelize'));
+
+  beforeEach(inject(function ($filter) {
+    filter = $filter('camelize');
+  }));
+
+  it('should camelize valid strings', function() {
+    expect(filter('a_simple_word')).toEqual('aSimpleWord');
+    expect(filter('a_medium_word_here')).toEqual('aMediumWordHere');
+    expect(filter('a sentence')).toEqual('aSentence');
+    expect(filter('ANUPPERCASEDWORDHERE')).toEqual('anuppercasedwordhere');
+    expect(filter('alowercasedword')).toEqual('alowercasedword');
+    expect(filter('     s')).toEqual('s');
+    expect(filter('  SOME WHITE SPACES  ')).toEqual('someWhiteSpaces');
+    expect(filter('  SOME-WHITE-SPACES  ')).toEqual('someWhiteSpaces');
+    expect(filter('-1  SOME-WHITE-SPACES0  2-')).toEqual('1SomeWhiteSpaces02');
+  });
+
+  it('should not camelize invalid strings', function() {
+    expect(filter(null)).not.toEqual('null');
+    expect(filter(undefined)).not.toEqual('undefined');
+    expect(filter('ANUPPERCASEDWORDHERe')).not.toEqual('aNUPPERCASEDWORDHERE');
+  });
+
+});
diff --git a/test/spec/filter/string/ucfirst.js b/test/spec/filter/string/ucfirst.js
index 80f1e2d..823b16b 100644
--- a/test/spec/filter/string/ucfirst.js
+++ b/test/spec/filter/string/ucfirst.js
@@ -13,7 +13,9 @@ describe('ucfirstFilter', function () {
   it('should get a string and return it uppercase each first letter', function() {
     expect(filter('a')).toEqual('A');
     expect(filter('foo bar baz')).toEqual('Foo Bar Baz');
+    expect(filter('foO baR bAz')).toEqual('Foo Bar Baz');
     expect(filter('lorem ipsum is simply dummy.... industry.')).toEqual('Lorem Ipsum Is Simply Dummy.... Industry.');
+    expect(filter('a medium senTence.', true)).toEqual('AMediumSentence');
   });
 
   it('should get a !string and not touch it', function() {
diff --git a/test/spec/filter/string/underscore.js b/test/spec/filter/string/underscore.js
new file mode 100644
index 0000000..cf472f3
--- /dev/null
+++ b/test/spec/filter/string/underscore.js
@@ -0,0 +1,29 @@
+'use strict';
+
+describe('underscoreFilter', function () {
+
+  var filter;
+
+  beforeEach(module('a8m.underscore'));
+
+  beforeEach(inject(function ($filter) {
+    filter = $filter('underscore');
+  }));
+
+  it('should underscore valid strings', function() {
+    expect(filter('ASimpleWord')).toEqual('a_simple_word');
+    expect(filter('aMediumWordHere')).toEqual('a_medium_word_here');
+    expect(filter('ANUPPERCASEDWORDHERE')).toEqual('a_n_u_p_p_e_r_c_a_s_e_d_w_o_r_d_h_e_r_e');
+    expect(filter('alowercasedword')).toEqual('alowercasedword');
+    expect(filter('  SOME WHITE SPACES  ')).toEqual('s_o_m_e_w_h_i_t_e_s_p_a_c_e_s');
+    expect(filter('  SOME-WHITE-SPACES  ')).toEqual('s_o_m_e_w_h_i_t_e_s_p_a_c_e_s');
+    expect(filter('1  SOME-WHITE-SPACES0  2')).toEqual('1_s_o_m_e_w_h_i_t_e_s_p_a_c_e_s02');
+
+  });
+
+  it('should not underscore invalid strings', function() {
+    expect(filter(null)).not.toEqual('null');
+    expect(filter(undefined)).not.toEqual('undefined');
+  });
+
+});