Artificial Intelligence and cognitive science are the twofields devoted to the study and development ofknowledge-based systems (KBS). Over the past 25years,researchers have proposed several approaches for modelingknowledge in KBS, including several kinds of formalism suchas semantic networks, frames, and logics. In the early1980s, J. F. Sowa introduced the conceptual graph (CG) theorywhich provides a knowledge representation frameworkconsisting of a form of logic with a graph notationandintegrating several features from semantic net and framerepresentations. Since that time, several research teamsover the world have been working on the application andextension of CG theory in various domains ranging fromnatural language processing to database modeling and machinelearning. This volume contains selected papers fromthe internationalconference on Conceptual Structures held in the city ofQuebec, Canada, August 4-7, 1993. The volume opens withinvited papers by J. F. Sowa, B. R. Gaines, and J. Barwise.