Methods, systems, and apparatus, including computer program products, for generating or using augmentation queries. In one aspect, augmentation queries are identified from user interactions or are machine generated. The augmentation queries can be stored in an augmentation query data store. When a user submits a search query to a search engine, the terms of the query, and optionally additional information, such as the geographic location from which the query is received or the language of the query, can be used to identify stored augmentation queries and select one or more similar augmentation queries. The selected augmentation queries, in turn, can be used by the search engine perform an augmented search operation.