Abstract: 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 an advertisement for presentation in a slot. The request includes selection criteria. At least one selection criterion indicates a preference for display advertisements. Using the selection criteria, without regard for the preference, candidate advertisements are identified from an inventory that includes both display and other types of advertisements. An auction is conducted, including the identified candidates, determining a winning bid. A type of advertisement for the winning bid is determined. When the winning bid is associated with a display advertisement, a display advertisement is provided.