diff --git a/config/env/default.js b/config/env/default.js
index 4ae53fafaa..8c7f2429ee 100644
--- a/config/env/default.js
+++ b/config/env/default.js
@@ -42,6 +42,9 @@ module.exports = {
   },
   logo: 'modules/core/client/img/brand/logo.png',
   favicon: 'modules/core/client/img/brand/favicon.ico',
+  illegalUsernames: ['meanjs', 'administrator', 'password', 'admin', 'user',
+                   'unknown', 'anonymous', 'null', 'undefined', 'api'
+                  ],
   uploads: {
     profileUpload: {
       dest: './modules/users/client/img/profile/uploads/', // Profile upload destination path
diff --git a/config/env/development.js b/config/env/development.js
index 93e2f7d743..da024eb886 100644
--- a/config/env/development.js
+++ b/config/env/development.js
@@ -75,7 +75,7 @@ module.exports = {
     options: {
       logResults: process.env.MONGO_SEED_LOG_RESULTS !== 'false',
       seedUser: {
-        username: process.env.MONGO_SEED_USER_USERNAME || 'user',
+        username: process.env.MONGO_SEED_USER_USERNAME || 'seeduser',
         provider: 'local',
         email: process.env.MONGO_SEED_USER_EMAIL || 'user@localhost.com',
         firstName: 'User',
@@ -84,7 +84,7 @@ module.exports = {
         roles: ['user']
       },
       seedAdmin: {
-        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'admin',
+        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'seedadmin',
         provider: 'local',
         email: process.env.MONGO_SEED_ADMIN_EMAIL || 'admin@localhost.com',
         firstName: 'Admin',
diff --git a/config/env/production.js b/config/env/production.js
index 333234c77f..f37f36b162 100644
--- a/config/env/production.js
+++ b/config/env/production.js
@@ -94,7 +94,7 @@ module.exports = {
     options: {
       logResults: process.env.MONGO_SEED_LOG_RESULTS !== 'false',
       seedUser: {
-        username: process.env.MONGO_SEED_USER_USERNAME || 'user',
+        username: process.env.MONGO_SEED_USER_USERNAME || 'seeduser',
         provider: 'local',
         email: process.env.MONGO_SEED_USER_EMAIL || 'user@localhost.com',
         firstName: 'User',
@@ -103,7 +103,7 @@ module.exports = {
         roles: ['user']
       },
       seedAdmin: {
-        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'admin',
+        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'seedadmin',
         provider: 'local',
         email: process.env.MONGO_SEED_ADMIN_EMAIL || 'admin@localhost.com',
         firstName: 'Admin',
diff --git a/config/env/test.js b/config/env/test.js
index c010177736..41c14ebf32 100644
--- a/config/env/test.js
+++ b/config/env/test.js
@@ -75,7 +75,7 @@ module.exports = {
     options: {
       logResults: process.env.MONGO_SEED_LOG_RESULTS !== 'false',
       seedUser: {
-        username: process.env.MONGO_SEED_USER_USERNAME || 'user',
+        username: process.env.MONGO_SEED_USER_USERNAME || 'seeduser',
         provider: 'local',
         email: process.env.MONGO_SEED_USER_EMAIL || 'user@localhost.com',
         firstName: 'User',
@@ -84,7 +84,7 @@ module.exports = {
         roles: ['user']
       },
       seedAdmin: {
-        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'admin',
+        username: process.env.MONGO_SEED_ADMIN_USERNAME || 'seedadmin',
         provider: 'local',
         email: process.env.MONGO_SEED_ADMIN_EMAIL || 'admin@localhost.com',
         firstName: 'Admin',
diff --git a/modules/core/tests/server/core.server.config.tests.js b/modules/core/tests/server/core.server.config.tests.js
index 4e8a3882dc..b7212e0317 100644
--- a/modules/core/tests/server/core.server.config.tests.js
+++ b/modules/core/tests/server/core.server.config.tests.js
@@ -82,7 +82,7 @@ describe('Configuration Tests:', function () {
     });
 
     it('should not be an admin user to begin with', function(done) {
-      User.find({ username: 'admin' }, function(err, users) {
+      User.find({ username: 'seedadmin' }, function(err, users) {
         should.not.exist(err);
         users.should.be.instanceof(Array).and.have.lengthOf(0);
         return done();
@@ -90,7 +90,7 @@ describe('Configuration Tests:', function () {
     });
 
     it('should not be a "regular" user to begin with', function(done) {
-      User.find({ username: 'user' }, function(err, users) {
+      User.find({ username: 'seeduser' }, function(err, users) {
         should.not.exist(err);
         users.should.be.instanceof(Array).and.have.lengthOf(0);
         return done();
diff --git a/modules/users/client/controllers/authentication.client.controller.js b/modules/users/client/controllers/authentication.client.controller.js
index 34ddeffd3f..23379ce384 100644
--- a/modules/users/client/controllers/authentication.client.controller.js
+++ b/modules/users/client/controllers/authentication.client.controller.js
@@ -15,6 +15,7 @@
     vm.signup = signup;
     vm.signin = signin;
     vm.callOauthProvider = callOauthProvider;
+    vm.usernameRegex = /^(?=[\w.-]+$)(?!.*[._-]{2})(?!\.)(?!.*\.$).{3,34}$/;
 
     // Get an eventual error defined in the URL query string:
     if ($location.search().err) {
diff --git a/modules/users/client/views/authentication/signup.client.view.html b/modules/users/client/views/authentication/signup.client.view.html
index 2c593322d9..5d57b519a2 100644
--- a/modules/users/client/views/authentication/signup.client.view.html
+++ b/modules/users/client/views/authentication/signup.client.view.html
@@ -27,9 +27,10 @@ <h3 class="col-xs-12 text-center">Or sign up using your email</h3>
         </div>
         <div class="form-group" show-errors>
           <label for="username">Username</label>
-          <input type="text" id="username" name="username" class="form-control" ng-model="vm.credentials.username" placeholder="Username" lowercase required>
+          <input type="text" id="username" name="username" class="form-control" ng-model="vm.credentials.username" ng-pattern="vm.usernameRegex" placeholder="Username" lowercase required>
           <div ng-messages="vm.userForm.username.$error" role="alert">
             <p class="help-block error-text" ng-message="required">Username is required.</p>
+            <p class="help-block error-text" ng-message="pattern">Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.</p>
           </div>
         </div>
         <div class="form-group" show-errors>
diff --git a/modules/users/server/models/user.server.model.js b/modules/users/server/models/user.server.model.js
index 16c3546e78..1dc4fc247f 100644
--- a/modules/users/server/models/user.server.model.js
+++ b/modules/users/server/models/user.server.model.js
@@ -29,6 +29,24 @@ var validateLocalStrategyEmail = function (email) {
   return ((this.provider !== 'local' && !this.updated) || validator.isEmail(email, { require_tld: false }));
 };
 
+/**
+ * A Validation function for username
+ * - at least 3 characters
+ * - only a-z0-9_-.
+ * - contain at least one alphanumeric character
+ * - not in list of illegal usernames
+ * - no consecutive dots: "." ok, ".." nope
+ * - not begin or end with "."
+ */
+
+var validateUsername = function(username) {
+  var usernameRegex = /^(?=[\w.-]+$)(?!.*[._-]{2})(?!\.)(?!.*\.$).{3,34}$/;
+  return (
+    this.provider !== 'local' ||
+    (username && usernameRegex.test(username) && config.illegalUsernames.indexOf(username) < 0)
+  );
+};
+
 /**
  * User Schema
  */
@@ -64,6 +82,7 @@ var UserSchema = new Schema({
     type: String,
     unique: 'Username already exists',
     required: 'Please fill in a username',
+    validate: [validateUsername, 'Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.'],
     lowercase: true,
     trim: true
   },
diff --git a/modules/users/tests/e2e/users.e2e.tests.js b/modules/users/tests/e2e/users.e2e.tests.js
index 6c232bfa4f..02d27ede02 100644
--- a/modules/users/tests/e2e/users.e2e.tests.js
+++ b/modules/users/tests/e2e/users.e2e.tests.js
@@ -113,6 +113,116 @@ describe('Users E2E Tests:', function () {
       expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Email address is invalid.');
     });
 
+    it('Should report invalid username - ".login"', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user1.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user1.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys(user1.email);
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('.login');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user1.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Email address error
+      expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.');
+    });
+
+    it('Should report invalid username - "login."', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user1.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user1.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys(user1.email);
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('login.');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user1.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Email address error
+      expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.');
+    });
+
+    it('Should report invalid username - "log..in"', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user1.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user1.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys(user1.email);
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('log..in');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user1.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Email address error
+      expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.');
+    });
+
+    it('Should report invalid username - "lo"', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user1.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user1.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys(user1.email);
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('lo');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user1.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Email address error
+      expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.');
+    });
+
+    it('Should report invalid username - "log$in"', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user1.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user1.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys(user1.email);
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('log$in');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user1.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Email address error
+      expect(element.all(by.css('.error-text')).get(0).getText()).toBe('Please enter a valid username: 3+ characters long, non restricted word, characters "_-.", no consecutive dots, does not begin or end with dots, letters a-z and numbers 0-9.');
+    });
+
+    it('Should signup username with . - "log.in"', function () {
+      browser.get('http://localhost:3001/authentication/signup');
+      // Enter First Name
+      element(by.model('vm.credentials.firstName')).sendKeys(user2.firstName);
+      // Enter Last Name
+      element(by.model('vm.credentials.lastName')).sendKeys(user2.lastName);
+      // Enter Email
+      element(by.model('vm.credentials.email')).sendKeys('someemail@meanjs.com');
+      // Enter Username
+      element(by.model('vm.credentials.username')).sendKeys('log.in');
+      // Enter Password
+      element(by.model('vm.credentials.password')).sendKeys(user2.password);
+      // Click Submit button
+      element(by.css('button[type=submit]')).click();
+      // Signup successful with username having .
+      expect(browser.getCurrentUrl()).toEqual('http://localhost:3001/');
+
+      signout();
+    });
+
     it('Should report missing username', function () {
       browser.get('http://localhost:3001/authentication/signup');
       // Enter First Name
diff --git a/modules/users/tests/server/user.server.model.tests.js b/modules/users/tests/server/user.server.model.tests.js
index 820389dba0..bac9e8b20a 100644
--- a/modules/users/tests/server/user.server.model.tests.js
+++ b/modules/users/tests/server/user.server.model.tests.js
@@ -5,7 +5,9 @@
  */
 var should = require('should'),
   mongoose = require('mongoose'),
-  User = mongoose.model('User');
+  User = mongoose.model('User'),
+  path = require('path'),
+  config = require(path.resolve('./config/config'));
 
 /**
  * Globals
@@ -643,6 +645,89 @@ describe('User Model Unit Tests:', function () {
 
   });
 
+  describe('Username Validation', function() {
+    it('should show error to save username beginning with .', function(done) {
+      var _user = new User(user1);
+
+      _user.username = '.login';
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should be able to show an error when try to save with not allowed username', function (done) {
+      var _user = new User(user1);
+
+      _user.username = config.illegalUsernames[Math.floor(Math.random() * config.illegalUsernames.length)];
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should show error to save username end with .', function(done) {
+      var _user = new User(user1);
+
+      _user.username = 'login.';
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should show error to save username with ..', function(done) {
+      var _user = new User(user1);
+
+      _user.username = 'log..in';
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should show error to save username shorter than 3 character', function(done) {
+      var _user = new User(user1);
+
+      _user.username = 'lo';
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should show error saving a username without at least one alphanumeric character', function(done) {
+      var _user = new User(user1);
+
+      _user.username = '-_-';
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should show error saving a username longer than 34 characters', function(done) {
+      var _user = new User(user1);
+
+      _user.username = 'l'.repeat(35);
+      _user.save(function(err) {
+        should.exist(err);
+        done();
+      });
+    });
+
+    it('should save username with dot', function(done) {
+      var _user = new User(user1);
+
+      _user.username = 'log.in';
+      _user.save(function(err) {
+        should.not.exist(err);
+        done();
+      });
+    });
+
+  });
+
   after(function (done) {
     User.remove().exec(done);
   });