Methods, systems, and apparatus include computer programs encoded on a computer-readable storage medium, including a method for providing content. A request is received for content to be displayed on a resource to a user. The user is identified. Candidate content items are identified from an inventory of content items that are responsive to the request. The candidate content items are evaluated including determining bid-eligible content items including content items that satisfy an eligibility threshold based on an eligibility status associated with a respective candidate content item. The eligibility status is based at least in part on results associated with past opportunities to present a content item to identified user. An auction is conducted to identify a winner from among the bid-eligible content items. The winning content item is provided responsive to the request. An eligibility status is updated for losing and winning content items in the auction.