This volume constitutes the edited proceedings of an interdisciplinary symposium on Methods of Heuristics, which was held at the University of Bern, Switzerland, from September 15 to 19, 1980. In organizing the symposium, the editors of the present volume were able to invite specialists from psychology, computer science, and mathematics. From their own perspective they made contributions to the central questions of the conference: What are heuristics, the methods and rules guiding discovery and problem solving in a variety of different fields? How did they develop in individual human beings and in the history of science? Is it possible to arrive at a commonly accepted definition of heuristics as the field unifying all these efforts, and, if yes, what are its basic characteristics?