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 the many and multi-faceted contributions to the scientific enterprise for which Werner Leinfellner is so widely known. We believe such a festschrift to be fitting and long overdue. Because of the breadth of Werner's professional associations, it was difficult to select representatives from among his many spheres of influence. We apologize to the many scholars who could not be in­ cluded because of time and space considerations. Finally, we wish to express appreciation to Dean John Guilds of the University of Arkansas for providing financial support early on in the evolution of this project, to Jennifer Bauman for her bravura performance in copy-editing the manuscripts, and to our publisher at Reidel for bringing this volume to press.