Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for processing voice commands. In one aspect, a method includes obtaining an occurrence count for terms that occur in resources that a search engine has identified as being responsive to an original search query, identifying a term that occurs in the resources, based on the occurrence count, providing the term and a control for display on a client device, the control being associated with the term and with promotion or demotion criteria, receiving a signal indicating that the user has selected the control, and automatically reformulating the original search query based on the term and the promotion or demotion criteria.