The volume contains a collection of papers presented at the Fourth International Symposium of the Special Research Unit Prevention and Intervention in Childhood and Adolescence at the Center for Interdisciplinary Research of the University of Bielefeld, in December 1988. The theoretical discussion

Thisseries is devoted to the publication of monographs, lecture resp. seminar notes, and other materials arising from programs of the OSU Mathemaical Research Institute. This includes proceedings of conferences or workshops held at the Institute, and other mathematical writings.