Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for determining a generalized edit distance for queries. In one aspect, a method includes selecting query pairs of consecutive queries, each query pair being a first query and a second query consecutively submitted as separate queries, each first and second query including at least one term. For each query pair, the method includes selecting term pairs from the query pair, each term pair being a first term in the first query and a second term in the second query; and determining a co-occurrence value for each term pair. The method also includes determining transition costs based on the co-occurrence values for term pairs, each transition cost indicative of a cost of transitioning from a first term in a first query to a second term in a second query consecutive to the first query.