We can deliver context-aware services to mobile users by dynamically computing the groups each user belongs to and providing
the user with the services associated with the selected groups. Recent progress in XML technology has enabled us to describe
the information needed for such processing precisely and flexibly. We analyzed the problems in applying XML technology to
context-aware service delivery and studied solutions. In particular we have developed (1) an algorithm for optimizing the
performance of our XML-based matching engine, and (2) tools for editing user profiles and service descriptions flexibly.