The Theory and Formal Methods Section of the Imperial College Department of Computing has an international reputation for research into the foundations of computer science, and the application of this theory to real computing problems. In March 1993 it held the first in a proposed series of workshops on theory and formal methods at the Isle of Thorns Conference Centre in Sussex, UK. Almost every member of the section contributed to the workshop, thereby providing comprehensive coverage of the work being done by this important research group. This volume contains revised versions of the papers presented at the workshop. They cover four main areas - semantics, concurrency, logic, and specification - with some papers spanning a variety of disciplines. The papers fall into two main categories: review papers which provide the reader with a good introduction to some of the specific areas being studied by the section, and research papers which give details of the latest results in these areas.