This book constitutes the refereed proceedings of the Third International Conference on Data Warehousing and Knowledge Discovery, DaWaK 2001, held in Munich, Germany in September 2001. The 33 revised full papers presented together with one invited paper were carefully reviewed and selected from more than 90 submissions. The papers are organized in topical sections on association rules, mining temporal patterns, data mining techniques, collaborative filtering and Web mining, visualization and matchmaking, development of data warehouses, maintenance of data warehouses, OLAP, and distributed data warehouses.