Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for distributing content are disclosed. In one aspect a distribution phrase that is used to distribute a content item for a content sponsor is accessed. Entities that correspond to the distribution phrase are identified and data specifying the entities are provided to the content sponsor. Data specifying at least one of the entities to be used as an entity distribution parameter for the content item are received from the content sponsor. A content item request that includes a resource identifier is received. A determination is made based, at least in part, on the resource identifier, that the resource references the at least one of the entities. The content item is distributed in response to the determination that the resource references the at least one of the entities.