Systems and a method for expanding a query are described. The method calculates a diversity index for a plurality of query terms that are included in a plurality of other queries associated with the query. The diversity index is a measure of diversity among the plurality of query terms and relates to differences among the plurality of query terms. The method further compares the diversity index to a threshold value. Finally, the method expands the query with one or more of the plurality of query terms based on the comparison.