This collection of articles contains contributions from a few of Werner Leinfellner's many friends and colleagues. Some of them are former students of Werner's. Others were colleagues of his at various American and European universities. Further, some have come to know Werner through his research, his long-standing editorship of Theory and Deci sion and his extensive participation in international conferences and congresses. The following articles are new to this volume. The areas covered are those in which Werner continues to play an active professional role. We offer them as a tribute to...