These volumes comprise the edited versions of the principal lectures and selected papers presented at the NATO Advanced Study Institute on Optimization and Decision Support Systems in Civil Engineering. The Institute was held in the Department of Civil Engineering at Heriot-Watt University, Edinburgh, United Kingdom, from June 25th to July 6th 1989. Both volumes reflect the full range of the systems approach to civil and structural engineering problems including: structural analysis and design; water resources engineering; geotechnical engineering; transportation and environmental engineering. This system approach, discussed in the first volume, includes a number of common threads: mathematical programming, game theory, utility theory, statistical decision theory, networks, and fuzzy logic. A most important feature of this volume is the examination of similar representations of different civil engineering problems and their solutions using general systems approaches. The decision support aspect of the institute is reflected in the second volume by the knowledge-based systems and their artificial intelligence approach. Papers discussing many aspects of knowledge-based systems in civil and structural engineering are included in the second volume.