This book presents the refereed proceedings of the Fourth International Symposium on Design and Implementation of Symbolic Computation Systems, DISCO '96, held in Karlsruhe, Germany, in September 1996.The volume includes four invited contributions surveying the state of the art in a particular subfield or pointing to some new research directions together with 31 revised full papers selected from a total of some 70 submissions. Many current aspects of mathematical software systems, as employed e.g. in computer algebra, automated theorem proving, or al- gebraic specification are addressed.