This volume is based on the proceedings of the International Workshop on Semantics of Specification Languages (SoSL), held in Utrecht, the Netherlands, 25-27 October 1993. The aim of the workshop - the first in a proposed series - was to assess various attempts to formally define specification languages, and to identify a programme of work for further investigation. There are currently no other workshops or conferences covering this area. The papers provide a comprehensive overview of research into this important topic, with particular emphasis on recent developments in formal proof systems, proof checking, type consistency, static semantics, and stepwise developments of specifications. In addition to the submitted papers the volume includes three invited papers, each of which outlines the development of the semantics of a major specification language.