This volume comprises the proceedings of the FirstAll-Berlin Workshop on Nonclassical Logics and InformationProcessing, held at the Free University of Berlin, November9-10, 1990.The scope of the ten papers in the volume is broad, coveringvarious different subfields of logic - particularlynonclassical logic - and its applications in artificialintelligence. The papers are grouped according to the fourmajor topics that emerged at the meeting: modal systems,logic programming, nonmonotonic logics, and proof theory.The classification is only a rough guide since the fourareas overlap considerably.