diff --git a/Gemfile b/Gemfile
index 672b002..537cabc 100644
--- a/Gemfile
+++ b/Gemfile
@@ -50,6 +50,7 @@ gem 'hamlit-rails'
 gem 'jekyll'
 gem 'jquery-rails'
 gem 'mini_magick'
+gem 'mobility'
 gem 'pundit'
 gem 'rails-i18n'
 gem 'rails_warden'
diff --git a/Gemfile.lock b/Gemfile.lock
index bef6cfc..7941b03 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -212,10 +212,13 @@ GEM
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
     mimemagic (0.3.3)
-    mini_magick (4.9.3)
+    mini_magick (4.9.4)
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.11.3)
+    mobility (0.8.7)
+      i18n (>= 0.6.10, < 2)
+      request_store (~> 1.0)
     multi_json (1.13.1)
     net-scp (2.0.0)
       net-ssh (>= 2.6.5, < 6.0.0)
@@ -277,6 +280,8 @@ GEM
       ffi (~> 1.0)
     rbnacl (4.0.2)
       ffi
+    request_store (1.4.1)
+      rack (>= 1.4)
     responders (3.0.0)
       actionpack (>= 5.0)
       railties (>= 5.0)
@@ -409,6 +414,7 @@ DEPENDENCIES
   letter_opener
   listen (>= 3.0.5, < 3.2)
   mini_magick
+  mobility
   pry
   puma (~> 3.7)
   pundit
diff --git a/app/controllers/sites_controller.rb b/app/controllers/sites_controller.rb
index ec7ad31..f3e2a6d 100644
--- a/app/controllers/sites_controller.rb
+++ b/app/controllers/sites_controller.rb
@@ -137,6 +137,6 @@ class SitesController < ApplicationController
   private
 
   def site_params
-    params.require(:site).permit(:name)
+    params.require(:site).permit(:name, :design_id)
   end
 end
diff --git a/app/models/design.rb b/app/models/design.rb
new file mode 100644
index 0000000..aeacb79
--- /dev/null
+++ b/app/models/design.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# El diseño de un sitio es la plantilla/tema.  En este modelo cargamos
+# las propiedades para poder verlas desde el panel y elegir un diseño
+# para el sitio.
+#
+# TODO: Agregar captura de pantalla con ActiveStorage
+class Design < ApplicationRecord
+  extend Mobility
+
+  translates :name, type: :string, locale_accessors: true
+  translates :description, type: :text, locale_accessors: true
+
+  has_many :sites
+
+  validates :name, presence: true, uniqueness: true
+  validates :gem, presence: true, uniqueness: true
+  validates :description, presence: true
+end
diff --git a/app/models/site.rb b/app/models/site.rb
index 24f80b0..0ed363a 100644
--- a/app/models/site.rb
+++ b/app/models/site.rb
@@ -6,9 +6,12 @@ class Site < ApplicationRecord
   include FriendlyId
 
   validates :name, uniqueness: true, hostname: true
+  validates :design_id, presence: true
 
   friendly_id :name, use: %i[finders]
 
+  belongs_to :design
+
   has_many :roles
   has_many :usuaries, -> { where('roles.rol = ?', 'usuarie') },
            through: :roles
diff --git a/app/views/sites/_form.haml b/app/views/sites/_form.haml
index 1f5650b..927cd2e 100644
--- a/app/views/sites/_form.haml
+++ b/app/views/sites/_form.haml
@@ -1,6 +1,29 @@
-= form_for @site do |f|
+= form_for site do |f|
   .form-group
-    = f.label :name
+    %h2= f.label :name
+    %p.lead= t('.help.name')
     = f.text_field :name, class: 'form-control'
+  .form-group
+    %h2= t('.design.title')
+    %p.lead= t('.help.design')
+    .row
+      -# Demasiado complejo para un f.collection_radio_buttons
+      - Design.all.each do |design|
+        .col
+          %h3
+            = f.radio_button :design_id, design.id,
+              checked: design.id == site.design_id,
+              disabled: design.disabled
+            = f.label "design_id_#{design.id}", design.name
+          = sanitize_markdown design.description,
+            tags: %w[p a strong em]
+
+          .btn-group{ role: 'group', 'aria-label': t('.design.actions') }
+            - if design.url
+              = link_to t('.design.url'), design.url,
+                target: '_blank', class: 'btn btn-info'
+            - if design.license
+              = link_to t('.design.license'), design.license,
+                target: '_blank', class: 'btn btn-info'
   .form-group
     = f.submit submit, class: 'btn btn-success'
diff --git a/app/views/sites/edit.haml b/app/views/sites/edit.haml
index a7e96a1..a461bb5 100644
--- a/app/views/sites/edit.haml
+++ b/app/views/sites/edit.haml
@@ -7,4 +7,4 @@
   .col
     %h1= t('.title', site: @site.name)
 
-    = render 'form', submit: t('.submit')
+    = render 'form', site: @site, submit: t('.submit')
diff --git a/app/views/sites/new.haml b/app/views/sites/new.haml
index 0b883c1..b5760f3 100644
--- a/app/views/sites/new.haml
+++ b/app/views/sites/new.haml
@@ -6,4 +6,4 @@
   .col
     %h1= t('.title')
 
-    = render 'form', submit: t('.submit')
+    = render 'form', site: @site, submit: t('.submit')
diff --git a/config/initializers/mobility.rb b/config/initializers/mobility.rb
new file mode 100644
index 0000000..8176045
--- /dev/null
+++ b/config/initializers/mobility.rb
@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+Mobility.configure do |config|
+  # Sets the default backend to use in models. This can be overridden in
+  # models by passing +backend: ...+ to +translates+.
+  config.default_backend = :key_value
+
+  # By default, Mobility uses the +translates+ class method in models to
+  # describe translated attributes, but you can configure this method to
+  # be whatever you like. This may be useful if using Mobility alongside
+  # another translation gem which uses the same method name.
+  config.accessor_method = :translates
+
+  # To query on translated attributes, you need to append a scope to
+  # your model. The name of this scope is +i18n+ by default, but this
+  # can be changed to something else.
+  config.query_method    = :i18n
+
+  # Uncomment and remove (or add) items to (from) this list to
+  # completely disable/enable plugins globally (so they cannot be used
+  # and are never even loaded). Note that if you remove an item from the
+  # list, you will not be able to use the plugin at all, and any options
+  # for the plugin will be ignored by models. (In most cases, you
+  # probably don't want to change this.)
+  #
+  # config.plugins = %i[
+  #   query
+  #   cache
+  #   dirty
+  #   fallbacks
+  #   presence
+  #   default
+  #   attribute_methods
+  #   fallthrough_accessors
+  #   locale_accessors
+  # ]
+
+  # The translation cache is on by default, but you can turn it off by
+  # uncommenting this line. (This may be helpful in debugging.)
+  #
+  # config.default_options[:cache] = false
+
+  # Dirty tracking is disabled by default. Uncomment this line to enable
+  # it.  If you enable this, you should also enable +locale_accessors+
+  # by default (see below).
+  #
+  # config.default_options[:dirty] = true
+
+  # No fallbacks are used by default. To define default fallbacks,
+  # uncomment and set the default fallback option value here. A "true"
+  # value will use whatever is defined by +I18n.fallbacks+ (if defined),
+  # or alternatively will fallback to your +I18n.default_locale+.
+  #
+  config.default_options[:fallbacks] = true
+
+  # The Presence plugin converts empty strings to nil when fetching and
+  # setting translations. By default it is on, uncomment this line to
+  # turn it off.
+  #
+  # config.default_options[:presence] = false
+
+  # Set a default value to use if the translation is nil. By default
+  # this is off, uncomment and set a default to use it across all models
+  # (you probably don't want to do that).
+  #
+  # config.default_options[:default] = ...
+
+  # Uncomment to enable locale_accessors by default on models. A true
+  # value will use the locales defined either in
+  # Rails.application.config.i18n.available_locales or
+  # I18n.available_locales.  If you want something else, pass an array
+  # of locales instead.
+  #
+  # config.default_options[:locale_accessors] = true
+
+  # Uncomment to enable fallthrough accessors by default on models. This
+  # will allow you to call any method with a suffix like _en or _pt_br,
+  # and Mobility will catch the suffix and convert it into a locale in
+  # +method_missing+. If you don't need this kind of open-ended
+  # fallthrough behavior, it's better to use locale_accessors instead
+  # (which define methods) since method_missing is very slow. (You can
+  # use both fallthrough and locale accessor plugins together without
+  # conflict.)
+  #
+  # Note: The dirty plugin enables fallthrough_accessors by default.
+  #
+  # config.default_options[:fallthrough_accessors] = true
+
+  # You can also include backend-specific default options. For example,
+  # if you want to default to using the text-type translation table with
+  # the KeyValue backend, you can set that as a default by uncommenting
+  # this line, or change it to :string to default to the string-type
+  # translation table instead. (For other backends, this option is
+  # ignored.)
+  #
+  # config.default_options[:type] = :text
+end
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 8f64db9..cdb5a45 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -158,6 +158,15 @@ en:
     edit:
       title: 'Edit %{site}'
       submit: 'Save changes'
+    form:
+      help:
+        name: "Your site's name.  It can only contain numbers and letters."
+        design: 'Select the design for your site.  You can change it later.  We add more designs from time to time.'
+      design:
+        title: 'Design'
+        actions: 'Information about this design'
+        url: 'Preview'
+        licencia: 'Read the license'
     fetch:
       title: 'Upgrade the site'
       help:
diff --git a/config/locales/es.yml b/config/locales/es.yml
index fc37c16..5cf84bd 100644
--- a/config/locales/es.yml
+++ b/config/locales/es.yml
@@ -163,6 +163,15 @@ es:
     edit:
       title: 'Editar %{site}'
       submit: 'Guardar cambios'
+    form:
+      help:
+        name: 'El nombre de tu sitio. Solo puede contener letras y números.'
+        design: 'Elegí el diseño que va a tener tu sitio aquí. Podés cambiarlo luego. De tanto en tanto vamos sumando diseños nuevos.'
+      design:
+        title: 'Diseño'
+        actions: 'Información sobre este diseño'
+        url: 'Vista previa'
+        licencia: 'Leer la licencia'
     fetch:
       title: 'Actualizar el sitio'
       help:
diff --git a/db/migrate/20190716195155_create_designs.rb b/db/migrate/20190716195155_create_designs.rb
new file mode 100644
index 0000000..b040749
--- /dev/null
+++ b/db/migrate/20190716195155_create_designs.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# Crea la tabla de diseños
+class CreateDesigns < ActiveRecord::Migration[5.2]
+  def change
+    create_table :designs do |t|
+      t.timestamps
+      t.string :name, unique: true
+      t.text   :description
+      t.string :gem, unique: true
+      t.string :url
+      t.string :license
+    end
+  end
+end
diff --git a/db/migrate/20190716195449_add_lang_to_usuaries.rb b/db/migrate/20190716195449_add_lang_to_usuaries.rb
new file mode 100644
index 0000000..598de77
--- /dev/null
+++ b/db/migrate/20190716195449_add_lang_to_usuaries.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+# Agrega la columna de idioma a cada usuarie para que pueda ver el sitio
+# y escribir artículos en su idioma.
+class AddLangToUsuaries < ActiveRecord::Migration[5.2]
+  def change
+    add_column :usuaries, :lang, :string, default: 'es'
+  end
+end
diff --git a/db/migrate/20190716195811_create_text_translations.rb b/db/migrate/20190716195811_create_text_translations.rb
new file mode 100644
index 0000000..caa129f
--- /dev/null
+++ b/db/migrate/20190716195811_create_text_translations.rb
@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# Tabla de traducción de textos utilizada por Mobility
+class CreateTextTranslations < ActiveRecord::Migration[5.2]
+  def change
+    create_table :mobility_text_translations do |t|
+      t.string :locale, null: false
+      t.string :key,    null: false
+      t.text :value
+      t.references :translatable, polymorphic: true, index: false
+      t.timestamps null: false
+    end
+    add_index :mobility_text_translations, %i[translatable_id translatable_type locale key], unique: true, name: :index_mobility_text_translations_on_keys
+    add_index :mobility_text_translations, %i[translatable_id translatable_type key], name: :index_mobility_text_translations_on_translatable_attribute
+  end
+end
diff --git a/db/migrate/20190716195812_create_string_translations.rb b/db/migrate/20190716195812_create_string_translations.rb
new file mode 100644
index 0000000..5389e02
--- /dev/null
+++ b/db/migrate/20190716195812_create_string_translations.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+# Tabla de traducción de cadenas usada por Mobility
+class CreateStringTranslations < ActiveRecord::Migration[5.2]
+  def change
+    create_table :mobility_string_translations do |t|
+      t.string :locale, null: false
+      t.string :key, null: false
+      t.string :value
+      t.references :translatable, polymorphic: true, index: false
+      t.timestamps null: false
+    end
+    add_index :mobility_string_translations, %i[translatable_id translatable_type locale key], unique: true, name: :index_mobility_string_translations_on_keys
+    add_index :mobility_string_translations, %i[translatable_id translatable_type key], name: :index_mobility_string_translations_on_translatable_attribute
+    add_index :mobility_string_translations, %i[translatable_type key value locale], name: :index_mobility_string_translations_on_query_keys
+  end
+end
diff --git a/db/migrate/20190716202024_add_design_to_sites.rb b/db/migrate/20190716202024_add_design_to_sites.rb
new file mode 100644
index 0000000..44958ea
--- /dev/null
+++ b/db/migrate/20190716202024_add_design_to_sites.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Los sitios tienen un diseño
+class AddDesignToSites < ActiveRecord::Migration[5.2]
+  def change
+    add_belongs_to :sites, :design, index: true
+  end
+end
diff --git a/db/migrate/20190717214308_add_disabled_to_designs.rb b/db/migrate/20190717214308_add_disabled_to_designs.rb
new file mode 100644
index 0000000..6432e34
--- /dev/null
+++ b/db/migrate/20190717214308_add_disabled_to_designs.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Algunos diseños están deshabilitados
+class AddDisabledToDesigns < ActiveRecord::Migration[5.2]
+  def change
+    add_column :designs, :disabled, :boolean, default: false
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 98e398c..0d9fb79 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -12,7 +12,43 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20_190_712_165_059) do
+ActiveRecord::Schema.define(version: 20_190_717_214_308) do
+  create_table 'designs', force: :cascade do |t|
+    t.datetime 'created_at', null: false
+    t.datetime 'updated_at', null: false
+    t.string 'name'
+    t.text 'description'
+    t.string 'gem'
+    t.string 'url'
+    t.string 'license'
+    t.boolean 'disabled', default: false
+  end
+
+  create_table 'mobility_string_translations', force: :cascade do |t|
+    t.string 'locale', null: false
+    t.string 'key', null: false
+    t.string 'value'
+    t.string 'translatable_type'
+    t.integer 'translatable_id'
+    t.datetime 'created_at', null: false
+    t.datetime 'updated_at', null: false
+    t.index %w[translatable_id translatable_type key], name: 'index_mobility_string_translations_on_translatable_attribute'
+    t.index %w[translatable_id translatable_type locale key], name: 'index_mobility_string_translations_on_keys', unique: true
+    t.index %w[translatable_type key value locale], name: 'index_mobility_string_translations_on_query_keys'
+  end
+
+  create_table 'mobility_text_translations', force: :cascade do |t|
+    t.string 'locale', null: false
+    t.string 'key', null: false
+    t.text 'value'
+    t.string 'translatable_type'
+    t.integer 'translatable_id'
+    t.datetime 'created_at', null: false
+    t.datetime 'updated_at', null: false
+    t.index %w[translatable_id translatable_type key], name: 'index_mobility_text_translations_on_translatable_attribute'
+    t.index %w[translatable_id translatable_type locale key], name: 'index_mobility_text_translations_on_keys', unique: true
+  end
+
   create_table 'roles', force: :cascade do |t|
     t.datetime 'created_at', null: false
     t.datetime 'updated_at', null: false
@@ -29,6 +65,8 @@ ActiveRecord::Schema.define(version: 20_190_712_165_059) do
     t.datetime 'created_at', null: false
     t.datetime 'updated_at', null: false
     t.string 'name'
+    t.integer 'design_id'
+    t.index ['design_id'], name: 'index_sites_on_design_id'
     t.index ['name'], name: 'index_sites_on_name', unique: true
   end
 
@@ -56,6 +94,7 @@ ActiveRecord::Schema.define(version: 20_190_712_165_059) do
     t.string 'invited_by_type'
     t.integer 'invited_by_id'
     t.integer 'invitations_count', default: 0
+    t.string 'lang', default: 'es'
     t.index ['confirmation_token'], name: 'index_usuaries_on_confirmation_token', unique: true
     t.index ['email'], name: 'index_usuaries_on_email', unique: true
     t.index ['invitation_token'], name: 'index_usuaries_on_invitation_token', unique: true
diff --git a/db/seeds.rb b/db/seeds.rb
index ebd1889..9e3d2c5 100644
--- a/db/seeds.rb
+++ b/db/seeds.rb
@@ -1,9 +1,9 @@
 # frozen_string_literal: true
 
-# This file should contain all the record creation needed to seed the database with its default values.
-# The data can then be loaded with the rails db:seed command (or created alongside the database with db:setup).
-#
-# Examples:
-#
-#   movies = Movie.create([{ name: 'Star Wars' }, { name: 'Lord of the Rings' }])
-#   Character.create(name: 'Luke', movie: movies.first)
+designs = YAML.safe_load(File.read('db/seeds/designs.yml'))
+
+designs.each do |d|
+  design = Design.find_or_create_by(gem: d['gem'])
+
+  design.update_attributes d
+end
diff --git a/db/seeds/designs.yml b/db/seeds/designs.yml
new file mode 100644
index 0000000..26f2e9a
--- /dev/null
+++ b/db/seeds/designs.yml
@@ -0,0 +1,22 @@
+---
+- name_en: 'My own design'
+  name_es: 'Mi propio diseño'
+  gem: 'sutty-theme-none'
+  url: 'https://sutty.nl'
+  disabled: true
+  description_en: "Your own design.  [This feature is in development, help us!]()"
+  description_es: "Tu propio diseño.  [Esta posibilidad está en desarrollo, ¡ayudanos!]()"
+- name_en: 'Minima'
+  name_es: 'Mínima'
+  gem: 'minima'
+  url: 'https://jekyll.github.io/minima/'
+  description_en: "Minima is the default design for Jekyll sites.  It's made for general-purpose writing."
+  description_es: 'Mínima es el diseño oficial de los sitios Jekyll, hecho para escritura de propósitos generales.'
+  license: 'https://github.com/jekyll/minima/blob/master/LICENSE.txt'
+- name_en: 'EDSL'
+  name_es: 'EDSL'
+  gem: 'sutty-theme-edsl'
+  url: 'https://endefensadelsl.org/'
+  description_en: "_En defensa del software libre_'s design"
+  description_es: 'El diseño de En defensa del software libre'
+  license: 'https://endefensadelsl.org/ppl_deed_es.html'
diff --git a/test/controllers/sites_controller_test.rb b/test/controllers/sites_controller_test.rb
index 2c3c334..058d20b 100644
--- a/test/controllers/sites_controller_test.rb
+++ b/test/controllers/sites_controller_test.rb
@@ -33,7 +33,8 @@ class SitesControllerTest < ActionDispatch::IntegrationTest
 
     post sites_url, headers: @authorization, params: {
       site: {
-        name: name
+        name: name,
+        design_id: create(:design).id
       }
     }
 
diff --git a/test/factories/design.rb b/test/factories/design.rb
new file mode 100644
index 0000000..b210b3a
--- /dev/null
+++ b/test/factories/design.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :design do
+    name { SecureRandom.hex }
+    description { SecureRandom.hex }
+    license { SecureRandom.hex }
+    gem { SecureRandom.hex }
+    url { SecureRandom.hex }
+    disabled { false }
+  end
+end
diff --git a/test/factories/site.rb b/test/factories/site.rb
index 9d80180..3593c9f 100644
--- a/test/factories/site.rb
+++ b/test/factories/site.rb
@@ -3,5 +3,6 @@
 FactoryBot.define do
   factory :site do
     name { "test-#{SecureRandom.hex}" }
+    design
   end
 end
diff --git a/test/models/design_test.rb b/test/models/design_test.rb
new file mode 100644
index 0000000..000be74
--- /dev/null
+++ b/test/models/design_test.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+class DesignTest < ActiveSupport::TestCase
+  test 'se pueden crear' do
+    design = create :design
+
+    assert design.valid?
+    assert design.persisted?
+  end
+end
diff --git a/test/models/site_test.rb b/test/models/site_test.rb
index 2040bd9..b74daaf 100644
--- a/test/models/site_test.rb
+++ b/test/models/site_test.rb
@@ -27,26 +27,30 @@ class SiteTest < ActiveSupport::TestCase
 
   test 'el nombre del sitio puede contener subdominios' do
     site = build :site, name: 'hola.chau'
+    site.validate
 
-    assert site.valid?
+    assert_not site.errors.messages[:name].present?
   end
 
   test 'el nombre del sitio no puede terminar con punto' do
     site = build :site, name: 'hola.chau.'
+    site.validate
 
-    assert_not site.valid?
+    assert site.errors.messages[:name].present?
   end
 
   test 'el nombre del sitio no puede contener wildcard' do
     site = build :site, name: '*.chau'
+    site.validate
 
-    assert_not site.valid?
+    assert site.errors.messages[:name].present?
   end
 
   test 'el nombre del sitio solo tiene letras, numeros y guiones' do
     site = build :site, name: 'A_Z!'
+    site.validate
 
-    assert_not site.valid?
+    assert site.errors.messages[:name].present?
   end
 
   test 'al destruir un sitio se eliminan los archivos' do