diff --git a/.env.test b/.env.test
index b57f52e3..e25c040a 100644
--- a/.env.test
+++ b/.env.test
@@ -1,3 +1,4 @@
 # Federation
 LOCAL_DOMAIN=cb6e6126.ngrok.io
 LOCAL_HTTPS=true
+OTP_SECRET=100c7faeef00caa29242f6b04156742bf76065771fd4117990c4282b8748ff3d99f8fdae97c982ab5bd2e6756a159121377cce4421f4a8ecd2d67bd7749a3fb4
diff --git a/app/assets/stylesheets/lists.scss b/app/assets/stylesheets/lists.scss
index eac9f5a2..13243aae 100644
--- a/app/assets/stylesheets/lists.scss
+++ b/app/assets/stylesheets/lists.scss
@@ -6,3 +6,12 @@
     margin: 0 5px;
   }
 }
+
+.recovery-codes {
+  column-count: 2;
+  height: 100px;
+  li {
+    list-style: decimal;
+    margin-left: 20px;
+  }
+}
diff --git a/app/controllers/auth/sessions_controller.rb b/app/controllers/auth/sessions_controller.rb
index 4184750f..a187ae6d 100644
--- a/app/controllers/auth/sessions_controller.rb
+++ b/app/controllers/auth/sessions_controller.rb
@@ -49,7 +49,8 @@ class Auth::SessionsController < Devise::SessionsController
   end
 
   def valid_otp_attempt?(user)
-    user.validate_and_consume_otp!(user_params[:otp_attempt])
+    user.validate_and_consume_otp!(user_params[:otp_attempt]) ||
+      user.invalidate_otp_backup_code!(user_params[:otp_attempt])
   end
 
   def authenticate_with_two_factor
diff --git a/app/controllers/settings/two_factor_auths_controller.rb b/app/controllers/settings/two_factor_auths_controller.rb
index 203d1fc4..bfe3868f 100644
--- a/app/controllers/settings/two_factor_auths_controller.rb
+++ b/app/controllers/settings/two_factor_auths_controller.rb
@@ -19,9 +19,9 @@ class Settings::TwoFactorAuthsController < ApplicationController
   def create
     if current_user.validate_and_consume_otp!(confirmation_params[:code])
       current_user.otp_required_for_login = true
+      @codes = current_user.generate_otp_backup_codes!
       current_user.save!
-
-      redirect_to settings_two_factor_auth_path, notice: I18n.t('two_factor_auth.enabled_success')
+      flash[:notice] = I18n.t('two_factor_auth.enabled_success')
     else
       @confirmation = Form::TwoFactorConfirmation.new
       set_qr_code
@@ -30,6 +30,12 @@ class Settings::TwoFactorAuthsController < ApplicationController
     end
   end
 
+  def recovery_codes
+    @codes = current_user.generate_otp_backup_codes!
+    current_user.save!
+    flash[:notice] = I18n.t('two_factor_auth.recovery_codes_regenerated')
+  end
+
   def disable
     current_user.otp_required_for_login = false
     current_user.save!
diff --git a/app/models/user.rb b/app/models/user.rb
index d2aa5d80..27a38674 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -5,7 +5,9 @@ class User < ApplicationRecord
 
   devise :registerable, :recoverable,
          :rememberable, :trackable, :validatable, :confirmable,
-         :two_factor_authenticatable, otp_secret_encryption_key: ENV['OTP_SECRET']
+         :two_factor_authenticatable, :two_factor_backupable,
+         otp_secret_encryption_key: ENV['OTP_SECRET'],
+         otp_number_of_backup_codes: 10
 
   belongs_to :account, inverse_of: :user
   accepts_nested_attributes_for :account
diff --git a/app/views/auth/sessions/two_factor.html.haml b/app/views/auth/sessions/two_factor.html.haml
index 1deff82b..3dec40c4 100644
--- a/app/views/auth/sessions/two_factor.html.haml
+++ b/app/views/auth/sessions/two_factor.html.haml
@@ -2,7 +2,9 @@
   = t('auth.login')
 
 = simple_form_for(resource, as: resource_name, url: session_path(resource_name), method: :post) do |f|
-  = f.input :otp_attempt, type: :number, placeholder: t('simple_form.labels.defaults.otp_attempt'), input_html: { 'aria-label' => t('simple_form.labels.defaults.otp_attempt') }, required: true, autofocus: true, autocomplete: 'off'
+  = f.input :otp_attempt, type: :number, placeholder: t('simple_form.labels.defaults.otp_attempt'),
+      input_html: { 'aria-label' => t('simple_form.labels.defaults.otp_attempt') }, required: true, autofocus: true, autocomplete: 'off',
+      hint: t('simple_form.hints.sessions.otp')
 
   .actions
     = f.button :button, t('auth.login'), type: :submit
diff --git a/app/views/settings/two_factor_auths/_recovery_codes.html.haml b/app/views/settings/two_factor_auths/_recovery_codes.html.haml
new file mode 100644
index 00000000..c23311e2
--- /dev/null
+++ b/app/views/settings/two_factor_auths/_recovery_codes.html.haml
@@ -0,0 +1,7 @@
+%p.hint= t('two_factor_auth.recovery_instructions')
+
+%h3= t('two_factor_auth.recovery_codes')
+%ol.recovery-codes
+  - @codes.each do |code|
+    %li
+      %samp= code
diff --git a/app/views/settings/two_factor_auths/create.html.haml b/app/views/settings/two_factor_auths/create.html.haml
new file mode 100644
index 00000000..8710b6e0
--- /dev/null
+++ b/app/views/settings/two_factor_auths/create.html.haml
@@ -0,0 +1,4 @@
+- content_for :page_title do
+  = t('settings.two_factor_auth')
+
+= render 'recovery_codes'
diff --git a/app/views/settings/two_factor_auths/recovery_codes.html.haml b/app/views/settings/two_factor_auths/recovery_codes.html.haml
new file mode 100644
index 00000000..8710b6e0
--- /dev/null
+++ b/app/views/settings/two_factor_auths/recovery_codes.html.haml
@@ -0,0 +1,4 @@
+- content_for :page_title do
+  = t('settings.two_factor_auth')
+
+= render 'recovery_codes'
diff --git a/app/views/settings/two_factor_auths/show.html.haml b/app/views/settings/two_factor_auths/show.html.haml
index 047fe0c5..bf19d24f 100644
--- a/app/views/settings/two_factor_auths/show.html.haml
+++ b/app/views/settings/two_factor_auths/show.html.haml
@@ -8,3 +8,8 @@
     = link_to t('two_factor_auth.disable'), disable_settings_two_factor_auth_path, data: { method: 'POST' }, class: 'block-button'
   - else
     = link_to t('two_factor_auth.setup'), new_settings_two_factor_auth_path, class: 'block-button'
+
+- if current_user.otp_required_for_login
+  .simple_form
+    %p.hint= t('two_factor_auth.lost_recovery_codes')
+    = link_to t('two_factor_auth.generate_recovery_codes'), recovery_codes_settings_two_factor_auth_path, data: { method: 'POST' }, class: 'block-button'
diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index 3c23e7b2..4754c2c8 100644
--- a/config/initializers/devise.rb
+++ b/config/initializers/devise.rb
@@ -1,6 +1,7 @@
 Devise.setup do |config|
   config.warden do |manager|
     manager.default_strategies(scope: :user).unshift :two_factor_authenticatable
+    manager.default_strategies(scope: :user).unshift :two_factor_backupable
   end
 
   # The secret key used by Devise. Devise uses this key to generate
diff --git a/config/locales/en.yml b/config/locales/en.yml
index e2f18739..474de398 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -290,8 +290,13 @@ en:
     disable: Disable
     enable: Enable
     enabled_success: Two-factor authentication successfully enabled
+    generate_recovery_codes: Generate Recovery Codes
     instructions_html: "<strong>Scan this QR code into Google Authenticator or a similiar TOTP app on your phone</strong>. From now on, that app will generate tokens that you will have to enter when logging in."
+    lost_recovery_codes: Recovery codes allow you to regain access to your account if you lose your phone. If you've lost your recovery codes, you can regenerate them here. Your old recovery codes will be invalidated.
     manual_instructions: 'If you can''t scan the QR code and need to enter it manually, here is the plain-text secret:'
+    recovery_codes: Recovery Codes
+    recovery_codes_regenerated: Recovery codes successfully regenerated
+    recovery_instructions: If you ever lose access to your phone, you can use one of the recovery codes below to regain access to your account. Keep the recovery codes safe, for example by printing them and storing them with other important documents.
     setup: Set up
     warning: If you cannot configure an authenticator app right now, you should click "disable" or you won't be able to login.
     wrong_code: The entered code was invalid! Are server time and device time correct?
diff --git a/config/locales/simple_form.en.yml b/config/locales/simple_form.en.yml
index 74649da5..c25407f2 100644
--- a/config/locales/simple_form.en.yml
+++ b/config/locales/simple_form.en.yml
@@ -10,6 +10,8 @@ en:
         note: At most 160 characters
       imports:
         data: CSV file exported from another Mastodon instance
+      sessions:
+        otp: Enter the Two-factor code from your phone or use one of your recovery codes.
     labels:
       defaults:
         avatar: Avatar
diff --git a/config/routes.rb b/config/routes.rb
index 045be940..8dcd4b33 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -64,6 +64,7 @@ Rails.application.routes.draw do
     resource :two_factor_auth, only: [:show, :new, :create] do
       member do
         post :disable
+        post :recovery_codes
       end
     end
   end
diff --git a/db/migrate/20170414080609_add_devise_two_factor_backupable_to_users.rb b/db/migrate/20170414080609_add_devise_two_factor_backupable_to_users.rb
new file mode 100644
index 00000000..65517d9f
--- /dev/null
+++ b/db/migrate/20170414080609_add_devise_two_factor_backupable_to_users.rb
@@ -0,0 +1,5 @@
+class AddDeviseTwoFactorBackupableToUsers < ActiveRecord::Migration[5.0]
+  def change
+    add_column :users, :otp_backup_codes, :string, array: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 2decf547..5f995ebd 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170406215816) do
+ActiveRecord::Schema.define(version: 20170414080609) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -313,6 +313,7 @@ ActiveRecord::Schema.define(version: 20170406215816) do
     t.integer  "consumed_timestep"
     t.boolean  "otp_required_for_login"
     t.datetime "last_emailed_at"
+    t.string   "otp_backup_codes",                                       array: true
     t.index ["account_id"], name: "index_users_on_account_id", using: :btree
     t.index ["confirmation_token"], name: "index_users_on_confirmation_token", unique: true, using: :btree
     t.index ["email"], name: "index_users_on_email", unique: true, using: :btree
diff --git a/spec/controllers/auth/sessions_controller_spec.rb b/spec/controllers/auth/sessions_controller_spec.rb
index c2a1fbe9..0ec0b8f2 100644
--- a/spec/controllers/auth/sessions_controller_spec.rb
+++ b/spec/controllers/auth/sessions_controller_spec.rb
@@ -5,7 +5,7 @@ RSpec.describe Auth::SessionsController, type: :controller do
 
   describe 'GET #new' do
     before do
-      request.env["devise.mapping"] = Devise.mappings[:user]
+      request.env['devise.mapping'] = Devise.mappings[:user]
     end
 
     it 'returns http success' do
@@ -15,19 +15,94 @@ RSpec.describe Auth::SessionsController, type: :controller do
   end
 
   describe 'POST #create' do
-    let(:user) { Fabricate(:user, email: 'foo@bar.com', password: 'abcdefgh') }
-
     before do
-      request.env["devise.mapping"] = Devise.mappings[:user]
-      post :create, params: { user: { email: user.email, password: user.password } }
+      request.env['devise.mapping'] = Devise.mappings[:user]
     end
 
-    it 'redirects to home' do
-      expect(response).to redirect_to(root_path)
+    context 'using password authentication' do
+      let(:user) { Fabricate(:user, email: 'foo@bar.com', password: 'abcdefgh') }
+
+      context 'using a valid password' do
+        before do
+          post :create, params: { user: { email: user.email, password: user.password } }
+        end
+
+        it 'redirects to home' do
+          expect(response).to redirect_to(root_path)
+        end
+
+        it 'logs the user in' do
+          expect(controller.current_user).to eq user
+        end
+      end
+
+      context 'using an invalid password' do
+        before do
+          post :create, params: { user: { email: user.email, password: 'wrongpw' } }
+        end
+
+        it 'shows a login error' do
+          expect(flash[:alert]).to match I18n.t('devise.failure.invalid', authentication_keys: 'Email')
+        end
+
+        it "doesn't log the user in" do
+          expect(controller.current_user).to be_nil
+        end
+      end
     end
 
-    it 'logs the user in' do
-      expect(controller.current_user).to eq user
+    context 'using two-factor authentication' do
+      let(:user) do
+        Fabricate(:user, email: 'x@y.com', password: 'abcdefgh',
+                         otp_required_for_login: true, otp_secret: User.generate_otp_secret(32))
+      end
+      let(:recovery_codes) do
+        codes = user.generate_otp_backup_codes!
+        user.save
+        return codes
+      end
+
+      context 'using a valid OTP' do
+        before do
+          post :create, params: { user: { otp_attempt: user.current_otp } }, session: { otp_user_id: user.id }
+        end
+
+        it 'redirects to home' do
+          expect(response).to redirect_to(root_path)
+        end
+
+        it 'logs the user in' do
+          expect(controller.current_user).to eq user
+        end
+      end
+
+      context 'using a valid recovery code' do
+        before do
+          post :create, params: { user: { otp_attempt: recovery_codes.first } }, session: { otp_user_id: user.id }
+        end
+
+        it 'redirects to home' do
+          expect(response).to redirect_to(root_path)
+        end
+
+        it 'logs the user in' do
+          expect(controller.current_user).to eq user
+        end
+      end
+
+      context 'using an invalid OTP' do
+        before do
+          post :create, params: { user: { otp_attempt: 'wrongotp' } }, session: { otp_user_id: user.id }
+        end
+
+        it 'shows a login error' do
+          expect(flash[:alert]).to match I18n.t('users.invalid_otp_token')
+        end
+
+        it "doesn't log the user in" do
+          expect(controller.current_user).to be_nil
+        end
+      end
     end
   end
 end
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index eb2a4aae..4ed1d5a0 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -1,6 +1,9 @@
 require 'rails_helper'
+require 'devise_two_factor/spec_helpers'
 
 RSpec.describe User, type: :model do
+  it_behaves_like 'two_factor_backupable'
+
   describe 'validations' do
     it 'is invalid without an account' do
       user = Fabricate.build(:user, account: nil)