diff --git a/app/assets/stylesheets/forms.scss b/app/assets/stylesheets/forms.scss
new file mode 100644
index 0000000..64fcb0b
--- /dev/null
+++ b/app/assets/stylesheets/forms.scss
@@ -0,0 +1,28 @@
+form {
+  .field_with_errors {
+    display: inline-block;
+  }
+}
+
+.layout-signup {
+  label {
+    display: none;
+  }
+
+  input[type=text], input[type=email], input[type=password] {
+    font-size: 1.25rem;
+    padding: 0.5rem 1rem;
+  }
+
+  span.at-sign, span.domain {
+    font-size: 1.25rem;
+  }
+
+  .error-msg {
+    color: #bc0101;
+  }
+
+  .actions {
+    margin-top: 2rem;
+  }
+}
diff --git a/app/controllers/signup_controller.rb b/app/controllers/signup_controller.rb
index 21dd7b3..237b77e 100644
--- a/app/controllers/signup_controller.rb
+++ b/app/controllers/signup_controller.rb
@@ -2,6 +2,7 @@ class SignupController < ApplicationController
   before_action :require_user_signed_out
   before_action :require_invitation
   before_action :set_invitation
+  before_action :set_new_user, only: ["steps", "validate"]
 
   layout "signup"
 
@@ -9,8 +10,61 @@ class SignupController < ApplicationController
     @invited_by_name = @invitation.user.address
   end
 
+  def steps
+    @step = params[:step].to_i
+    http_status :not_found unless [1,2,3].include?(@step)
+    @validation_error = session[:validation_error]
+  end
+
+  def validate
+    session[:validation_error] = nil
+
+    case user_params.keys.first
+    when "cn"
+      @user.cn = user_params[:cn]
+      @user.valid?
+      session[:new_user] = @user
+
+      if @user.errors[:cn].present?
+        session[:validation_error] = @user.errors[:cn].first # Store user including validation errors
+        redirect_to signup_steps_path(1) and return
+      else
+        redirect_to signup_steps_path(2) and return
+      end
+    when "email"
+      @user.email = user_params[:email]
+      @user.valid?
+      session[:new_user] = @user
+
+      if @user.errors[:email].present?
+        session[:validation_error] = @user.errors[:email].first # Store user including validation errors
+        redirect_to signup_steps_path(2) and return
+      else
+        redirect_to signup_steps_path(3) and return
+      end
+    when "password"
+      @user.password = user_params[:password]
+      @user.password_confirmation = user_params[:password]
+      @user.valid?
+      session[:new_user] = @user
+
+      if @user.errors[:password].present?
+        session[:validation_error] = @user.errors[:password].first # Store user including validation errors
+        redirect_to signup_steps_path(3) and return
+      else
+        complete_signup
+        msg = "Almost done! We have sent you an email to confirm your address."
+        redirect_to(check_your_email_path, notice: msg) and return
+      end
+    end
+  end
+
   private
 
+  def user_params
+    params.require(:user).permit(:cn, :email, :password)
+  end
+
   def require_invitation
     if session[:invitation_token].blank?
       flash.now[:alert] = "You need an invitation to sign up for an account."
@@ -30,4 +84,27 @@ class SignupController < ApplicationController
   def set_invitation
     @invitation = Invitation.find_by(token: session[:invitation_token])
   end
+
+  def set_new_user
+    if session[:new_user].present?
+      @user = User.new(session[:new_user])
+    else
+      @user = User.new(ou: "kosmos.org")
+    end
+  end
+
+  def complete_signup
+    @user.save!
+    session[:new_user] = nil
+    session[:validation_error] = nil
+
+    CreateAccount.call(
+      username: @user.cn,
+      email: @user.email,
+      password: @user.password
+    )
+
+    @invitation.update_attributes invited_user_id: @user.id,
+      used_at: DateTime.now
+  end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index e6f80f0..b2f3693 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -2,6 +2,10 @@ class User < ApplicationRecord
   # Relations
   has_many :invitations, dependent: :destroy
 
+  validates_uniqueness_of :cn
+  validates_uniqueness_of :email
+  validates_length_of :cn, :minimum => 3
+
   # Include default devise modules. Others available are:
   # :confirmable, :lockable, :timeoutable, :trackable and :omniauthable
   devise :ldap_authenticatable,
@@ -40,4 +44,9 @@ class User < ApplicationRecord
   def address
     "#{self.cn}@#{self.ou}"
   end
+
+  def valid_attribute?(attribute_name)
+    self.valid?
+    self.errors[attribute_name].blank?
+  end
 end
diff --git a/app/views/layouts/signup.html.erb b/app/views/layouts/signup.html.erb
index 05fbf73..1a49165 100644
--- a/app/views/layouts/signup.html.erb
+++ b/app/views/layouts/signup.html.erb
@@ -11,7 +11,7 @@
     <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
   </head>
 
-  <body>
+  <body class="layout-signup">
     <div id="wrapper">
       <header>
         <h1>
diff --git a/app/views/shared/status_not_found.html.erb b/app/views/shared/status_not_found.html.erb
new file mode 100644
index 0000000..c31810c
--- /dev/null
+++ b/app/views/shared/status_not_found.html.erb
@@ -0,0 +1,2 @@
+<h2>Not found</h2>
+<p>Sorry, this page does not exist.</p>
diff --git a/app/views/signup/index.html.erb b/app/views/signup/index.html.erb
index f3782fa..f3d8b80 100644
--- a/app/views/signup/index.html.erb
+++ b/app/views/signup/index.html.erb
@@ -8,5 +8,5 @@
   by invitation. Seems like you have good friends!
 </p>
 <p>
-  <%= link_to "Get started", signup_path, class: "next-step" %>
+  <%= link_to "Get started", signup_steps_path(1), class: "next-step" %>
 </p>
diff --git a/app/views/signup/steps.html.erb b/app/views/signup/steps.html.erb
new file mode 100644
index 0000000..107ed5a
--- /dev/null
+++ b/app/views/signup/steps.html.erb
@@ -0,0 +1,55 @@
+<% case @step %>
+<% when 1 %>
+  <h2>Choose a username</h2>
+  <%= form_for @user, :url => signup_validate_url do |f| %>
+    <div class="field">
+      <p>
+        <%= f.label :cn, 'Username' %><br />
+        <%= f.text_field :cn, autofocus: true, autocomplete: "username" %>
+        <span class="at-sign">@</span>
+        <span class="domain">kosmos.org</span>
+      </p>
+      <% if @validation_error.present? %>
+        <p class="error-msg">Username <%= @validation_error %></p>
+      <% end %>
+    </div>
+    <div class="actions">
+      <p><%= f.submit "Continue" %></p>
+    </div>
+  <% end %>
+
+<% when 2 %>
+  <h2>What's your email?</h2>
+  <%= form_for @user, :url => signup_validate_url do |f| %>
+    <div class="field">
+      <p>
+        <%= f.label :email, 'Email address' %><br />
+        <%= f.email_field :email, autofocus: true, autocomplete: "email" %>
+      </p>
+      <% if @validation_error.present? %>
+        <p class="error-msg">Email <%= @validation_error %></p>
+      <% end %>
+    </div>
+    <div class="actions">
+      <p><%= f.submit "Continue" %></p>
+    </div>
+  <% end %>
+
+<% when 3 %>
+  <h2>Choose a password</h2>
+
+  <%= form_for @user, :url => signup_validate_url do |f| %>
+    <div class="field">
+      <p>
+        <%= f.label :password, 'Password' %><br />
+        <%= f.password_field :password, autofocus: true %>
+      </p>
+      <% if @validation_error.present? %>
+        <p class="error-msg">Password <%= @validation_error %></p>
+      <% end %>
+    </div>
+    <div class="actions">
+      <p><%= f.submit "Continue" %></p>
+    </div>
+  <% end %>
+<% end %>
diff --git a/config/routes.rb b/config/routes.rb
index f6aa90c..bdefef0 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -5,6 +5,8 @@ Rails.application.routes.draw do
   get 'check_your_email', to: 'welcome#check_your_email'
 
   get 'signup', to: 'signup#index'
+  match 'signup/:step', to: 'signup#steps', as: :signup_steps, via: [:get, :post]
+  post 'signup_validate', to: 'signup#validate'
 
   get 'settings', to: 'settings#index'
   post 'settings_reset_password', to: 'settings#reset_password'