This book constitutes the refereed proceedings of the 17th International Conference on Database and Expert Systems Applications, DEXA 2006. The book presents 90 revised full papers together with 1 invited paper. The papers are organized in topical sections on XML, data and information, data mining and data warehouses, database applications, WWW, bioinformatics, process automation and workflow, knowledge management and expert systems, database theory, query processing, and privacy and security.