This volume contains the revised versions of 28 papers presented at the third workshop on Computer Science Logic held in Kaiserslautern, FRG, October 2-6, 1989. These proceedings cover a wide range of topics both from theoretical and applied areas of computer science. More specifically, the papers deal with problems arising at the border of logic and computer science, e.g. in complexity, data base theory, logic programming, artificial intelligece, and temporal logic. The volume should be of interest to all logicians and computer scientists working in the above field.