This volume constitutes the refereed proceedings of the Fourth International Conference on Conceptual Structures, ICCS '96, held in Sydney, Australia, in August 1996.<BR>The book presents five full papers by the
invited speakers together with 15 revised full papers selected for presentation at the conference from a respectable number of submissions. The issues addressed are natural language processing, information retrieval, graph
operations, conceptual graph and Peirce theory, knowledge acquisition, theorem proving and CG programming, and order-based organisation and encoding.