Annotation. This volume contains papers presented at the Third International Conference on Computing and Information, ICCI '91, held at Carleton University in Ottawa, Canada, May 27-29, 1991. The conference was organized by the School of Computer Science at Carleton University, and was sponsored by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Carleton University. ICCI '91 was an international forum for the presentation of original results in research, development, and applications in computing and information processing. The conference was aimed at both practitioners and theoreticians, and was organized into five streams: - Algorithms and complexity, - Databases and information systems, - Parallel processing and systems, - Distributed computing and systems, - Expert systems, artificial intelligence. This volume contains three invited papers, by E.C.R. Hehner, R.L. Probert, and S.J. Smith, and 71 selected papers.