diff --git a/.rubocop.yml b/.rubocop.yml
index e3b44c70..2b20bbb3 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -19,6 +19,7 @@ Metrics/AbcSize:
     - 'app/controllers/posts_controller.rb'
     - 'app/controllers/invitadxs_controller.rb'
     - 'app/controllers/i18n_controller.rb'
+    - 'app/controllers/usuaries_controller.rb'
 
 Metrics/MethodLength:
   Exclude:
diff --git a/Gemfile b/Gemfile
index 4026dcd2..10313805 100644
--- a/Gemfile
+++ b/Gemfile
@@ -41,6 +41,7 @@ gem 'carrierwave-i18n'
 gem 'commonmarker'
 gem 'devise'
 gem 'devise-i18n'
+gem 'devise_invitable'
 gem 'email_address'
 gem 'exception_notification'
 gem 'font-awesome-rails'
diff --git a/Gemfile.lock b/Gemfile.lock
index dc95aedf..67cc2bcd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -106,6 +106,9 @@ GEM
       warden (~> 1.2.3)
     devise-i18n (1.8.0)
       devise (>= 4.6)
+    devise_invitable (2.0.1)
+      actionmailer (>= 5.0)
+      devise (>= 4.6)
     dotenv (2.7.2)
     dotenv-rails (2.7.2)
       dotenv (= 2.7.2)
@@ -363,6 +366,7 @@ DEPENDENCIES
   commonmarker
   devise
   devise-i18n
+  devise_invitable
   dotenv-rails
   ed25519
   email_address
diff --git a/app/controllers/usuaries_controller.rb b/app/controllers/usuaries_controller.rb
index 1aef1b6b..85208992 100644
--- a/app/controllers/usuaries_controller.rb
+++ b/app/controllers/usuaries_controller.rb
@@ -51,4 +51,59 @@ class UsuariesController < ApplicationController
 
     redirect_to site_usuaries_path
   end
+
+  # Poder invitar
+  def invite
+    @site = find_site
+    site_usuarie = SiteUsuarie.new(@site, current_usuarie)
+    authorize site_usuarie
+
+    @policy = policy(site_usuarie)
+  end
+
+  # Envía las invitaciones
+  def send_invitations
+    @site = find_site
+    authorize SiteUsuarie.new(@site, current_usuarie)
+
+    # Enviar la invitación si es necesario y agregar al sitio
+    #
+    # TODO: Pedir consentimiento para agregar a un sitio!
+    invitaciones.each do |invitacion|
+      # Si la cuenta no existe, envía una invitación por correo
+      usuarie = Usuarie.invite! email: invitacion.address
+
+      # No invitar al sitio si ya estaba en la lista!
+      unless @site.invitade?(usuarie) || @site.usuarie?(usuarie)
+        @site.send(invited_as) << usuarie
+      end
+    end
+
+    redirect_to site_usuaries_path(@site)
+  end
+
+  private
+
+  # Traer todas las invitaciones que al menos tengan usuarie y dominio
+  def invitaciones
+    # XXX: Podríamos usar EmailAddress pero hace chequeos más lentos
+    i = params[:invitaciones].split("\n").map do |m|
+      Mail::Address.new m
+        rescue Mail::Field::IncompleteParseError
+          nil
+    end.compact
+
+    i.select do |m|
+      m.local && m.domain
+    end
+  end
+
+  # El tipo de invitación que tenemos que enviar, si alguien mandó
+  # cualquier cosa, usamos el privilegio menor.
+  def invited_as
+    invited_as = params[:invited_as].try(:to_sym)
+    invited_as = :invitades unless %i[usuaries invitades].include?(invited_as)
+
+    invited_as
+  end
 end
diff --git a/app/models/usuarie.rb b/app/models/usuarie.rb
index b0f2e3b6..8fea94a2 100644
--- a/app/models/usuarie.rb
+++ b/app/models/usuarie.rb
@@ -2,7 +2,7 @@
 
 # Usuarie de la plataforma
 class Usuarie < ApplicationRecord
-  devise :database_authenticatable,
+  devise :invitable, :database_authenticatable,
          :recoverable, :rememberable, :validatable,
          :confirmable, :lockable, :registerable
 
diff --git a/app/policies/site_usuarie_policy.rb b/app/policies/site_usuarie_policy.rb
index d3734803..ded45407 100644
--- a/app/policies/site_usuarie_policy.rb
+++ b/app/policies/site_usuarie_policy.rb
@@ -27,6 +27,14 @@ class SiteUsuariePolicy
     usuarie?
   end
 
+  def invite?
+    usuarie?
+  end
+
+  def send_invitations?
+    usuarie?
+  end
+
   private
 
   def usuarie?
diff --git a/app/views/devise/invitations/edit.haml b/app/views/devise/invitations/edit.haml
new file mode 100644
index 00000000..f2dd5b8e
--- /dev/null
+++ b/app/views/devise/invitations/edit.haml
@@ -0,0 +1,16 @@
+.row.align-items-center.justify-content-center.full-height
+  .col-md-6.align-self-center
+    %h2= t 'devise.invitations.edit.header'
+    = form_for(resource, as: resource_name, url: invitation_path(resource_name), html: { method: :put }) do |f|
+      = render 'devise/shared/error_messages', resource: resource
+      = f.hidden_field :invitation_token, readonly: true
+      - if f.object.class.require_password_on_accepting
+        .form-group
+          = f.label :password
+          = f.password_field :password, class: 'form-control'
+        .form-group
+          = f.label :password_confirmation
+          = f.password_field :password_confirmation, class: 'form-control'
+      .actions
+        = f.submit t('devise.invitations.edit.submit_button'),
+          class: 'btn btn-lg btn-primary btn-block'
diff --git a/app/views/devise/invitations/new.haml b/app/views/devise/invitations/new.haml
new file mode 100644
index 00000000..e5116dc4
--- /dev/null
+++ b/app/views/devise/invitations/new.haml
@@ -0,0 +1,12 @@
+.row.align-items-center.justify-content-center.full-height
+  .col-md-6.align-self-center
+    %h2= t 'devise.invitations.new.header'
+    = form_for(resource, as: resource_name, url: invitation_path(resource_name), html: { method: :post }) do |f|
+      = render 'devise/shared/error_messages', resource: resource
+      - resource.class.invite_key_fields.each do |field|
+        .form-group
+          = f.label field
+          = f.text_field field, class: 'form-control'
+      .actions
+        = f.submit t('devise.invitations.new.submit_button'),
+          class: 'btn btn-lg btn-primary btn-block'
diff --git a/app/views/devise/mailer/invitation_instructions.haml b/app/views/devise/mailer/invitation_instructions.haml
new file mode 100644
index 00000000..f2f42219
--- /dev/null
+++ b/app/views/devise/mailer/invitation_instructions.haml
@@ -0,0 +1,6 @@
+%p= t("devise.mailer.invitation_instructions.hello", email: @resource.email)
+%p= t("devise.mailer.invitation_instructions.someone_invited_you", url: root_url)
+%p= link_to t("devise.mailer.invitation_instructions.accept"), accept_invitation_url(@resource, invitation_token: @token)
+- if @resource.invitation_due_at
+  %p= t("devise.mailer.invitation_instructions.accept_until", due_date: l(@resource.invitation_due_at, format: :'devise.mailer.invitation_instructions.accept_until_format'))
+%p= t("devise.mailer.invitation_instructions.ignore")
diff --git a/app/views/devise/mailer/invitation_instructions.text.haml b/app/views/devise/mailer/invitation_instructions.text.haml
new file mode 100644
index 00000000..a9d23d3f
--- /dev/null
+++ b/app/views/devise/mailer/invitation_instructions.text.haml
@@ -0,0 +1,6 @@
+= t("devise.mailer.invitation_instructions.hello", email: @resource.email)
+= t("devise.mailer.invitation_instructions.someone_invited_you", url: root_url)
+= accept_invitation_url(@resource, invitation_token: @token)
+- if @resource.invitation_due_at
+  = t("devise.mailer.invitation_instructions.accept_until", due_date: l(@resource.invitation_due_at, format: :'devise.mailer.invitation_instructions.accept_until_format'))
+= t("devise.mailer.invitation_instructions.ignore")
diff --git a/app/views/layouts/mailer.text.erb b/app/views/layouts/mailer.text.erb
deleted file mode 100644
index 37f0bddb..00000000
--- a/app/views/layouts/mailer.text.erb
+++ /dev/null
@@ -1 +0,0 @@
-<%= yield %>
diff --git a/app/views/usuaries/index.haml b/app/views/usuaries/index.haml
index 733e4342..f8408da6 100644
--- a/app/views/usuaries/index.haml
+++ b/app/views/usuaries/index.haml
@@ -14,7 +14,15 @@
   .col
     -# Una tabla de usuaries y otra de invitades, con acciones
     - %i[usuaries invitades].each do |u|
-      %h2= t(".#{u.to_s}")
+      %h2
+        = t(".#{u.to_s}")
+        .btn-group{role: 'group', 'aria-label': t('.actions')}
+          - if @policy.invite?
+            = link_to t('.invite.text'),
+              site_usuaries_invite_path(@site, invite_as: u.to_s),
+              class: 'btn btn-success',
+              data: { toggle: 'tooltip' },
+              title: t('.help.invite', invite_as: u.to_s)
       %p= t(".help.#{u.to_s}")
       %table.table.table-striped.table-condensed
         %tbody
@@ -23,7 +31,7 @@
               -# TODO: avatares
               %td= cuenta.email
               %td
-                .btn-group{role: 'group', 'aria-label': t('.actions')}
+                .btn-group{role: 'group', 'aria-label': t('.individual_actions')}
                   - if @policy.demote? && @site.usuarie?(cuenta)
                     = link_to t('.demote.text'),
                       site_usuarie_demote_path(@site, cuenta),
diff --git a/app/views/usuaries/invite.haml b/app/views/usuaries/invite.haml
new file mode 100644
index 00000000..49d83205
--- /dev/null
+++ b/app/views/usuaries/invite.haml
@@ -0,0 +1,26 @@
+- invite_as = t("usuaries.invite_as.#{params[:invite_as]}")
+.row
+  .col
+    = render 'layouts/breadcrumb',
+      crumbs: [ link_to(t('sites.index'), sites_path),
+      @site.name,
+      link_to(t('posts.index'),
+      site_usuaries_path(@site)),
+      t('.title', invite_as: invite_as) ]
+    = render 'layouts/help', help: t('help.breadcrumbs')
+.row
+  .col
+    %h1= t('.title', invite_as: invite_as)
+
+.row
+  .col
+    = form_with url: site_usuaries_invite_path(@site) do |f|
+      = f.hidden_field :invite_as, value: params[:invite_as]
+      .form-group
+        = f.label :invitaciones do
+          = t('.invitaciones')
+          %small.text-muted.form-text= t('.help.invitaciones',
+            invite_as: invite_as)
+        = f.text_area :invitaciones, class: 'form-control'
+      .form-group
+        = f.submit t('.submit'), class: 'btn btn-success'
diff --git a/config/initializers/devise.rb b/config/initializers/devise.rb
index 256b37e1..a963058b 100644
--- a/config/initializers/devise.rb
+++ b/config/initializers/devise.rb
@@ -136,6 +136,58 @@ Devise.setup do |config|
   # Send a notification email when the user's password is changed.
   config.send_password_change_notification = true
 
+  # ==> Configuration for :invitable
+  # The period the generated invitation token is valid.  After this
+  # period, the invited resource won't be able to accept the invitation.
+  # When invite_for is 0 (the default), the invitation won't expire.
+  config.invite_for = 2.weeks
+
+  # Number of invitations users can send.
+  # - If invitation_limit is nil, there is no limit for invitations,
+  # users can send unlimited invitations, invitation_limit column is not
+  # used.
+  # - If invitation_limit is 0, users can't send invitations by default.
+  # - If invitation_limit n > 0, users can send n invitations.
+  # You can change invitation_limit column for some users so they can
+  # send more or less invitations, even with global invitation_limit = 0
+  # Default: nil
+  config.invitation_limit = 0
+
+  # The key to be used to check existing users when sending an
+  # invitation and the regexp used to test it when validate_on_invite is
+  # not set.
+  # config.invite_key = { email: /\A[^@]+@[^@]+\z/ }
+  # config.invite_key = { email: /\A[^@]+@[^@]+\z/, username: nil }
+
+  # Ensure that invited record is valid.
+  # The invitation won't be sent if this check fails.
+  # Default: false
+  # config.validate_on_invite = true
+
+  # Resend invitation if user with invited status is invited again
+  # Default: true
+  # config.resend_invitation = false
+
+  # The class name of the inviting model. If this is nil,
+  # the #invited_by association is declared to be polymorphic.
+  # Default: nil
+  # config.invited_by_class_name = 'User'
+
+  # The foreign key to the inviting model (if invited_by_class_name is
+  # set)
+  # Default: :invited_by_id
+  # config.invited_by_foreign_key = :invited_by_id
+
+  # The column name used for counter_cache column. If this is nil,
+  # the #invited_by association is declared without counter_cache.
+  # Default: nil
+  # config.invited_by_counter_cache = :invitations_count
+
+  # Auto-login after the user accepts the invite. If this is false,
+  # the user will need to manually log in after accepting the invite.
+  # Default: true
+  # config.allow_insecure_sign_in_after_accept = false
+
   # ==> Configuration for :confirmable
   # A period that the user is allowed to access the website even without
   # confirming their account. For instance, if set to 2.days, the user
diff --git a/config/locales/devise_invitable.en.yml b/config/locales/devise_invitable.en.yml
new file mode 100644
index 00000000..f6bfee40
--- /dev/null
+++ b/config/locales/devise_invitable.en.yml
@@ -0,0 +1,31 @@
+en:
+  devise:
+    failure:
+      invited: "You have a pending invitation, accept it to finish creating your account."
+    invitations:
+      send_instructions: "An invitation email has been sent to %{email}."
+      invitation_token_invalid: "The invitation token provided is not valid!"
+      updated: "Your password was set successfully. You are now signed in."
+      updated_not_active: "Your password was set successfully."
+      no_invitations_remaining: "No invitations remaining"
+      invitation_removed: "Your invitation was removed."
+      new:
+        header: "Send invitation"
+        submit_button: "Send an invitation"
+      edit:
+        header: "Set your password"
+        submit_button: "Set my password"
+    mailer:
+      invitation_instructions:
+        subject: "Invitation instructions"
+        hello: "Hello %{email}"
+        someone_invited_you: "Someone has invited you to %{url}, you can accept it through the link below."
+        accept: "Accept invitation"
+        accept_until: "This invitation will be due in %{due_date}."
+        ignore: "If you don't want to accept the invitation, please ignore this email. Your account won't be created until you access the link above and set your password."
+  time:
+    formats:
+      devise:
+        mailer:
+          invitation_instructions:
+            accept_until_format: "%B %d, %Y %I:%M %p"
diff --git a/config/locales/devise_invitable.es.yml b/config/locales/devise_invitable.es.yml
new file mode 100644
index 00000000..f12bf2a2
--- /dev/null
+++ b/config/locales/devise_invitable.es.yml
@@ -0,0 +1,31 @@
+es:
+  devise:
+    failure:
+      invited: "Tenés una invitación pendiente, aceptala para terminar de crear tu cuenta."
+    invitations:
+      send_instructions: "Hemos enviado una invitación a %{email}."
+      invitation_token_invalid: "¡El código de invitación no es válido!"
+      updated: "Configuraste tu contraseña correctamente, a partir de ahora podés ingresar."
+      updated_not_active: "Configuraste tu contraseña correctamente."
+      no_invitations_remaining: "No te quedan invitaciones"
+      invitation_removed: "La invitación ha sido eliminada."
+      new:
+        header: "Invitar a alguien"
+        submit_button: "Enviar la invitación"
+      edit:
+        header: "Configura tu contraseña"
+        submit_button: "Configurar mi contraseña"
+    mailer:
+      invitation_instructions:
+        subject: "Invitación"
+        hello: "Hola %{email}"
+        someone_invited_you: "Alguien te ha invitado a colaborar en %{url}, podés aceptar la invitación con el enlace a continuación."
+        accept: "Aceptar la invitación"
+        accept_until: "La invitación vencerá en %{due_date}."
+        ignore: "Si no querés aceptar la invitación, por favor ignora este correo. Tu cuenta no será creada hasta que aceptes la invitación y configures una contraseña."
+  time:
+    formats:
+      devise:
+        mailer:
+          invitation_instructions:
+            accept_until_format: "%d/%m/%Y a las %H:%M"
diff --git a/config/locales/en.yml b/config/locales/en.yml
index ae0fdff7..3675665b 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -259,6 +259,9 @@ en:
     destroy: Delete
     confirm_destroy: Are you sure?
   usuaries:
+    invite_as:
+      usuaries: users
+      invitades: guests
     index:
       help:
         self: Self-manage who has access to this site
@@ -267,6 +270,7 @@ en:
         invitades: 'Guests can only create new posts and edit those authored by them. Any change needs review and approval by a user.'
         demote: Removes privileges for this user
         promote: Gives privileges to this guest
+        invite: 'Invites %{invite_as} to this site'
       title: Users and Guests
       usuaries: Users
       invitades: Guests
@@ -279,3 +283,11 @@ en:
       promote:
         text: 'Convert to user'
         confirm: 'Convert to user?  They will gain full access to self-manage this site.'
+      invite:
+        text: 'Invite'
+    invite:
+      title: 'Invite %{invite_as}'
+      help:
+        invitaciones: 'You can invite new %{invite_as} by entering an email address per line.  They will receive an email with your invitation and decide if they want to accept or not.'
+      invitaciones: Send invitations to these addresses
+      submit: Send invitations
diff --git a/config/locales/es.yml b/config/locales/es.yml
index f34996a8..8900479a 100644
--- a/config/locales/es.yml
+++ b/config/locales/es.yml
@@ -266,6 +266,9 @@ es:
     destroy: Borrar
     confirm_destroy: ¿Estás segurx?
   usuaries:
+    invite_as:
+      usuaries: usuaries
+      invitades: invitades
     index:
       help:
         self: Gestionar quiénes tienen acceso a este sitio
@@ -274,6 +277,7 @@ es:
         invitades: 'Les invitades sólo pueden crear artículos nuevos y modificar los que cargaron.  Todos los cambios que hagan necesitan la revisión y aprobación de une usuarie.'
         demote: Quita privilegios a este usuarie
         promote: Otorga privilegios a este invitade
+        invite: 'Invita %{invite_as} a colaborar en este sitio'
       title: Usuaries e invitades
       usuaries: Usuaries
       invitades: Invitades
@@ -286,3 +290,11 @@ es:
       promote:
         text: 'Convertir en usuarie'
         confirm: '¿Convertir en usuarie?  Ganará acceso a la gestión completa del sitio.'
+      invite:
+        text: 'Invitar'
+    invite:
+      title: 'Invitar %{invite_as}'
+      help:
+        invitaciones: 'Invita nueves %{invite_as} ingresando una dirección de correo electrónico por línea.  Recibirán un correo con tu invitación y podrán aceptarla o no.'
+      invitaciones: Invitar a estas direcciones
+      submit: Enviar invitaciones
diff --git a/config/routes.rb b/config/routes.rb
index 3f225453..d7d5cd5e 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -17,6 +17,8 @@ Rails.application.routes.draw do
     get 'public/:type/:basename', to: 'sites#send_public_file'
 
     # Gestionar usuaries
+    get 'usuaries/invite', to: 'usuaries#invite'
+    post 'usuaries/invite', to: 'usuaries#send_invitations'
     resources :usuaries do
       patch 'demote', to: 'usuaries#demote'
       patch 'promote', to: 'usuaries#promote'
diff --git a/db/migrate/20190705215536_devise_invitable_add_to_usuaries.rb b/db/migrate/20190705215536_devise_invitable_add_to_usuaries.rb
new file mode 100644
index 00000000..466f94db
--- /dev/null
+++ b/db/migrate/20190705215536_devise_invitable_add_to_usuaries.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# Agregar gestión de invitaciones a usuaries
+class DeviseInvitableAddToUsuaries < ActiveRecord::Migration[5.2]
+  def up
+    change_table :usuaries do |t|
+      t.string     :invitation_token
+      t.datetime   :invitation_created_at
+      t.datetime   :invitation_sent_at
+      t.datetime   :invitation_accepted_at
+      t.integer    :invitation_limit
+      t.references :invited_by, polymorphic: true
+      t.integer    :invitations_count, default: 0
+      t.index      :invitations_count
+      t.index      :invitation_token, unique: true # for invitable
+      t.index      :invited_by_id
+    end
+  end
+
+  def down
+    change_table :usuaries do |t|
+      t.remove_references :invited_by, polymorphic: true
+      t.remove :invitations_count, :invitation_limit, :invitation_sent_at, :invitation_accepted_at, :invitation_token, :invitation_created_at
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index c1b435fe..4a6bfe39 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -12,7 +12,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20_190_705_195_758) do
+ActiveRecord::Schema.define(version: 20_190_705_215_536) do
   create_table 'invitades_sites', id: false, force: :cascade do |t|
     t.integer 'site_id'
     t.integer 'usuarie_id'
@@ -48,8 +48,20 @@ ActiveRecord::Schema.define(version: 20_190_705_195_758) do
     t.string 'unlock_token'
     t.datetime 'locked_at'
     t.boolean 'acepta_politicas_de_privacidad', default: false
+    t.string 'invitation_token'
+    t.datetime 'invitation_created_at'
+    t.datetime 'invitation_sent_at'
+    t.datetime 'invitation_accepted_at'
+    t.integer 'invitation_limit'
+    t.string 'invited_by_type'
+    t.integer 'invited_by_id'
+    t.integer 'invitations_count', default: 0
     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
+    t.index ['invitations_count'], name: 'index_usuaries_on_invitations_count'
+    t.index ['invited_by_id'], name: 'index_usuaries_on_invited_by_id'
+    t.index %w[invited_by_type invited_by_id], name: 'index_usuaries_on_invited_by_type_and_invited_by_id'
     t.index ['reset_password_token'], name: 'index_usuaries_on_reset_password_token', unique: true
     t.index ['unlock_token'], name: 'index_usuaries_on_unlock_token', unique: true
   end
diff --git a/doc/autenticacion.md b/doc/autenticacion.md
index c5b38133..93335fad 100644
--- a/doc/autenticacion.md
+++ b/doc/autenticacion.md
@@ -43,3 +43,26 @@ está en su lista de invitade.  Lo mismo para usuaries.
 
 Les usuaries pueden bloquear invitades y a otres usuaries, y sumar
 usuaries e invitades a su sitio (via correo de invitación).
+
+## Invitaciones a sitios
+
+### Enviar invitación
+
+Desde la gestión del sitio se puede invitar a nueves usuaries e
+invitades.  Se les envía un correo (y cuando tengamos sistema de
+notificaciones, una notificación) donde pueden confirmar su
+participación.
+
+Si no tienen cuenta, tienen que registrarse completando los datos en el
+momento, sino se pueden loguear normalmente.
+
+Si ya están logueades, se acepta la invitación inmediatamente.
+
+### Invitades desde la web
+
+Al publicar la URL de invitación, les invitades se puedan registrar
+por su cuenta.  Solo deben completar sus datos (correo y contraseña) y
+reciben un correo de confirmación.
+
+En la configuración del sitio hay que distinguir entre invitades por
+invitación o por registro automático.