This volume contains revised versions of 43 papers presented during the 21st Annual Conference of the Gesellschaft fur Klassifikation (GfKl), the German Classification Society. The conference took place at the University of Pots dam (Germany) in March 1997; the local organizer was Prof. 1. Balderjahn, Chair of Business Administration and Marketing at Potsdam. The scientific program of the conference included 103 plenary and con tributed papers, software and book presentations as well as special (tutorial) courses. Researchers and practitioners interested in data analysis and clus tering...