diff --git a/app/controllers/user_admin_controller.rb b/app/controllers/user_admin_controller.rb
--- a/app/controllers/user_admin_controller.rb
+++ b/app/controllers/user_admin_controller.rb
@@ -16,6 +16,7 @@
   def list
     @users = User.find(:all)
     @hidden_columns = ['hashed_password', 'salt', 'created_at', 'updated_at']
+    @contests = Contest.all(:conditions => {:enabled => true})
   end
 
   def active
@@ -150,6 +151,68 @@
       @changed = true
     end
   end
+  
+  # contest management
+
+  def add_to_contest
+    user = User.find(params[:id])
+    contest = Contest.find(params[:contest_id])
+    if user and contest
+      user.contests << contest
+    end
+    redirect_to :action => 'list'
+  end
+
+  def remove_from_contest
+    user = User.find(params[:id])
+    contest = Contest.find(params[:contest_id])
+    if user and contest
+      user.contests.delete(contest)
+    end
+    redirect_to :action => 'list'
+  end
+
+  def contest_management
+  end
+
+  def manage_contest
+    contest = Contest.find(params[:contest][:id])
+    if !contest
+      flash[:notice] = 'You did not choose the contest.'
+      redirect_to :action => 'contest_management' and return
+    end
+
+    operation = params[:operation]
+
+    if operation!='add' and operation!='remove'
+      flash[:notice] = 'You did not choose the operation to perform.'
+      redirect_to :action => 'contest_management' and return
+    end
+
+    lines = params[:login_list]
+    if !lines or lines.blank?
+      flash[:notice] = 'You entered an empty list.'
+      redirect_to :action => 'contest_management' and return
+    end
+
+    note = []
+    lines.split("\n").each do |line|
+      puts line
+      user = User.find_by_login(line.chomp)
+      puts user
+      if user
+        if operation=='add'
+          user.contests << contest
+        else
+          user.contests.delete(contest)
+        end
+        note << user.login
+      end
+    end
+    flash[:notice] = 'User(s) ' + note.join(', ') + 
+      ' were successfully modified.  ' 
+    redirect_to :action => 'contest_management'    
+  end
 
   # admin management
 
diff --git a/app/models/problem.rb b/app/models/problem.rb
--- a/app/models/problem.rb
+++ b/app/models/problem.rb
@@ -1,7 +1,7 @@
 class Problem < ActiveRecord::Base
 
   belongs_to :description
-  has_and_belongs_to_many :contests
+  has_and_belongs_to_many :contests, :uniq => true
   has_many :test_pairs, :dependent => :delete_all
 
   validates_presence_of :name
diff --git a/app/models/user.rb b/app/models/user.rb
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -21,7 +21,7 @@
   belongs_to :site
   belongs_to :country
 
-  has_and_belongs_to_many :contests
+  has_and_belongs_to_many :contests, :uniq => true
 
   named_scope :activated_users, :conditions => {:activated => true}
 
diff --git a/app/views/main/list.html.haml b/app/views/main/list.html.haml
--- a/app/views/main/list.html.haml
+++ b/app/views/main/list.html.haml
@@ -32,15 +32,16 @@
       = render :partial => 'problem', :collection => @problems
   - else
     - @contest_problems.each do |cp|
-      %h2{:class =>'contest-title'}
-        = "#{cp[:contest] ? cp[:contest].title : 'Public problems'}"
-      %table.info
-        %tr.info-head
-          %th
-          %th Tasks
-          %th # of sub(s)
-          %th Results
-        = render :partial => 'problem', :collection => cp[:problems]
+      - if cp[:problems].length > 0
+        %h2{:class =>'contest-title'}
+          = "#{cp[:contest] ? cp[:contest].title : 'Public problems'}"
+        %table.info
+          %tr.info-head
+            %th
+            %th Tasks
+            %th # of sub(s)
+            %th Results
+          = render :partial => 'problem', :collection => cp[:problems]
 
 
 %hr/
diff --git a/app/views/user_admin/admin.html.haml b/app/views/user_admin/admin.html.haml
--- a/app/views/user_admin/admin.html.haml
+++ b/app/views/user_admin/admin.html.haml
@@ -1,7 +1,7 @@
 %h1 Administrators
 
-%table
-  %tr
+%table{:class => 'info'}
+  %tr{:class => 'info-head'}
     %th #
     %th Login
     %th Full name
diff --git a/app/views/user_admin/contest_management.html.haml b/app/views/user_admin/contest_management.html.haml
new file mode 100644
--- /dev/null
+++ b/app/views/user_admin/contest_management.html.haml
@@ -0,0 +1,16 @@
+%h1 Bulk edit users in contests
+
+- form_tag :action => 'manage_contest' do
+  List users' login below; one per line.
+  %br/
+  = text_area_tag 'login_list', nil, :rows => 25, :cols => 80
+  %br/
+  You want to
+  = select(nil,"operation",[['add users to','add'],['remove users from','remove']])
+  contest
+  = select("contest","id",Contest.all.collect {|c| [c.title, c.id]})
+  &nbsp;&nbsp;&nbsp;&nbsp;
+  = submit_tag "Perform action", :confirm => 'Are you sure?'
+
+%hr/
+= link_to '[go back to index]', :action => 'index'
diff --git a/app/views/user_admin/list.rhtml b/app/views/user_admin/list.rhtml
--- a/app/views/user_admin/list.rhtml
+++ b/app/views/user_admin/list.rhtml
@@ -33,27 +33,51 @@
   <%= link_to '[View administrators]', :action => 'admin' %>
   <%= link_to '[Random passwords]', :action => 'random_all_passwords' %>
   <%= link_to '[View active users]', :action => 'active' %>
+  <% if Configuration.multicontests? %>
+    <%= link_to '[Manage bulk users in contests]', :action => 'contest_management' %>
+  <% end %>
 </div>
 
-<table>
-  <tr>
-  <% for column in User.content_columns %>
-    <% if !@hidden_columns.index(column.name) %>
-      <th><%= column.human_name %></th>
+<table class="info">
+  <tr class="info-head">
+    <% for column in User.content_columns %>
+      <% if !@hidden_columns.index(column.name) %>
+        <th><%= column.human_name %></th>
+      <% end %>
     <% end %>
-  <% end %>
+    <th></th>
+    <th></th>
+    <th></th>
+    <% if Configuration.multicontests? %>
+      <th>Contests</th>
+      <th>Other enabled contests</th>
+    <% end %>
   </tr>
   
 <% for user in @users %>
-  <tr>
-  <% for column in User.content_columns %>
-    <% if !@hidden_columns.index(column.name) %>
-      <td><%=h user.send(column.name) %></td>
+  <tr class="info-<%= cycle("odd","even") %>">
+    <% for column in User.content_columns %>
+      <% if !@hidden_columns.index(column.name) %>
+        <td><%=h user.send(column.name) %></td>
+      <% end %>
     <% end %>
-  <% end %>
     <td><%= link_to 'Show', :action => 'show', :id => user %></td>
     <td><%= link_to 'Edit', :action => 'edit', :id => user %></td>
     <td><%= link_to 'Destroy', { :action => 'destroy', :id => user }, :confirm => 'Are you sure?', :method => :post %></td>
+    <% if Configuration.multicontests? %>
+      <td>
+        <% user.contests.each do |contest| %>
+	  <%= contest.name %> [<%= link_to 'x', :action => 'remove_from_contest', :id => user.id, :contest_id => contest.id %>]
+        <% end %>
+      </td>
+      <td>	
+	<% @contests.each do |contest| %>
+	  <% if not user.contests.all.find {|c| c.id==contest.id } %>
+  	    <%= contest.name %> [<%= link_to '+', :action => 'add_to_contest', :id => user.id, :contest_id => contest.id %>]
+          <% end %>
+	<% end %>  
+      </td>
+    <% end %>
   </tr>
 <% end %>
 </table>