Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for content presentation. In one aspect, a method includes receiving a request for a content item to be presented to a user; for a collection of content items, identifying one or more candidate content items including using image keywords derived from images associated with the user to identify the one or more candidate content items; selecting a content item responsive to the content request from the candidate content items; and sending the selected content item for presentation to the user.