Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for enhancing selecting relevant and diverse advertisements. In one aspect, a method includes receiving an initial query, selecting one or more additional queries relating to the initial query, including selecting additional queries having a greatest commerciality, identifying one or more content items for each of the additional queries, the one or more content items forming a content block, and providing a content block and an associated additional query to a client device to be displayed along with search results associated with the initial query.