Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for information retrieval. In one aspect, a method includes receiving a flight search query, the flight search query identifying a plurality of flight parameters including a departure location, a destination location, and at least one date; obtaining a plurality of flight search results that satisfy the flight search query; grouping the plurality of flight search results into groups based at least in part on calculated similarity between flight search results of the plurality of flight search results, wherein the similarity is based on a combination of a plurality of features of the respective flight itineraries of the flight search results; and providing the plurality of flight search results for display in a flight search results interface including providing at least one group result of the generated groups of flight search results.