Query routing in peer-to-peer systems is based onthe peers' content summaries. For the sake of scalability,summaries are built at a "peer level." The coarseness of peer level summaries limits their ability to route queries accurately to peers sharing relevant contents. We propose to improve the quality of each peer's summary by grouping its contents and summarizing each group individually. To enhance grouping effectiveness, we incorporate information about real-world term distributions into group generation. Experimental results show that our techniques significantly improve query routing accuracy with little cost.