This book contains the papers presented at the international symposium Polycrys talline Semiconductors - Grain Boundaries and Interfaces (POLYSE '88) that was held in Malente, FRG, from August 29 to September 2, 1988. This conference has two roots: Firstly, it is a successor to a conference on polycrystalline semi conductors held in Perpignan, France, in 1982 and to a summer school in Erice, Italy, in 1984. Secondly, it continues a series of German workshops on polycrys talline semiconductors, which have been organized every year since 1983 by two of the present editors (H. P. S. and J. H. W....