diff --git a/app/assets/javascripts/users_select.js.coffee b/app/assets/javascripts/users_select.js.coffee
index 8dad599a..45e4a17d 100644
--- a/app/assets/javascripts/users_select.js.coffee
+++ b/app/assets/javascripts/users_select.js.coffee
@@ -16,7 +16,7 @@ $ ->
 
   $('.ajax-users-select').select2
     placeholder: "Search for a user"
-    multiple: true
+    multiple: $('.ajax-users-select').hasClass('multiselect')
     minimumInputLength: 0
     ajax: # instead of writing the function to execute the request we use Select2's convenient helper
       url: "/api/v3/users.json"
diff --git a/app/controllers/teams/members_controller.rb b/app/controllers/teams/members_controller.rb
index 4bd70fd7..f87d422f 100644
--- a/app/controllers/teams/members_controller.rb
+++ b/app/controllers/teams/members_controller.rb
@@ -13,7 +13,7 @@ class Teams::MembersController < Teams::ApplicationController
 
   def create
     unless params[:user_ids].blank?
-      user_ids = params[:user_ids]
+      user_ids = params[:user_ids].split(',')
       access = params[:default_project_access]
       is_admin = params[:group_admin]
       user_team.add_members(user_ids, access, is_admin)
diff --git a/app/helpers/application_helper.rb b/app/helpers/application_helper.rb
index 45972612..7567da15 100644
--- a/app/helpers/application_helper.rb
+++ b/app/helpers/application_helper.rb
@@ -170,7 +170,9 @@ module ApplicationHelper
 
   alias_method :url_to_image, :image_url
 
-  def users_select_tag(id)
-    hidden_field_tag(id, '', class: "ajax-users-select")
+  def users_select_tag(id, opts = {})
+    css_class = "ajax-users-select"
+    css_class << " multiselect" if opts[:multiple]
+    hidden_field_tag(id, '', class: css_class)
   end
 end
diff --git a/app/models/user_team.rb b/app/models/user_team.rb
index 0cb84edd..d5b75851 100644
--- a/app/models/user_team.rb
+++ b/app/models/user_team.rb
@@ -69,6 +69,9 @@ class UserTeam < ActiveRecord::Base
   end
 
   def add_members(users, access, group_admin)
+    # reject existing users
+    users.reject! { |id| member_ids.include?(id.to_i) }
+
     users.each do |user|
       add_member(user, access, group_admin)
     end
diff --git a/app/views/team_members/_form.html.haml b/app/views/team_members/_form.html.haml
index e45c6f6f..4e8f6770 100644
--- a/app/views/team_members/_form.html.haml
+++ b/app/views/team_members/_form.html.haml
@@ -12,8 +12,7 @@
   .clearfix
     = f.label :user_ids, "People"
     .input
-      = users_select_tag(:user_ids)
-      -#= select_tag(:user_ids, options_from_collection_for_select(User.active.not_in_project(@project).alphabetically, :id, :name_with_username), {data: {placeholder: "Select users"}, class: "chosen xxlarge", multiple: true})
+      = users_select_tag(:user_ids, multiple: true)
 
   %h6 2. Set access level for them
   .clearfix
diff --git a/app/views/teams/members/new.html.haml b/app/views/teams/members/new.html.haml
index 1a03cea0..9b9b3cef 100644
--- a/app/views/teams/members/new.html.haml
+++ b/app/views/teams/members/new.html.haml
@@ -20,7 +20,8 @@
           %td= @team.admin?(member) ? "Admin" : "Member"
           %td
       %tr
-        %td= select_tag :user_ids, options_from_collection_for_select(@users , :id, :name_with_username), multiple: true, data: {placeholder: 'Select users'}, class: 'chosen span5'
+        %td
+          = users_select_tag(:user_ids, multiple: true)
         %td= select_tag :default_project_access, options_for_select(Project.access_options), {class: "project-access-select chosen span3" }
         %td
           %span= check_box_tag :group_admin