This book constitutes the refereed proceedings of the 17th International Conference on Database and Expert Systems Applications, DEXA 2006, held in Krakow, Poland in September 2006.The 90 revised full papers presented together with 1 invited paper were carefully reviewed and selected from 296 submissions. The papers are organized in topical sections on XML, data and information, datamining and data warehouses, database applications, WWW, bioinformatics, process automation and workflow, knowledge