A set of queries, such as a search log, is divided into commercial queries and non-commercial queries. A first set of query communities is determined from the non-commercial queries and a second set is determined from the commercial queries. The query communities are correlated based on the users who submitted the queries and instances where a query from the first set of query communities was followed by a query from the second set to generate a mapping between the first set of query communities and the second set. Later, a non-commercial query is received from a user, and the mapping is used to predict one or more commercial queries that the user is likely to submit in the future based on the non-commercial query. One or more of the commercial queries are presented to the user according to the mapping with search results responsive to the non-commercial query.