A search query is submitted to one or more information sources associated with a category of the query. The category of the query is indicated by a query ontology that relates queries to query categories. The information sources represent information sources from which a high percentage of search results for queries associated with the category are retrieved. For instance, the category of the query is identified by identifying categories corresponding to variations of the query, where each variation represents a combination of the terms within the query, and where the categories of the variations are assumed to be the categories of the query. Information sources associated with the query categories are identified, and the query is submitted to the identified information sources. Submitting the query to the identified information sources may cause search results retrieved for the query to more closely reflect search results desired by a user that specified the query.