This book provides a select collection of papers written by experts on multiple criteria decision aid and presented at the International Conference on Methods and Applications of Multiple Criteria Decision Making (May 1997, Mons, Belgium). It covers methodological aspects of decision theory and comparisons between theoretical approaches to multiple criteria decision making. The material includes choice procedures, Multiple Attribute Utility Theory (MAUT), outranking methods like ELECTRE and PROMETHEE, verbal decision analysis and Data Envelopment Analysis (DEA). Audience: This book is mathematically oriented but the results are also of great interest to engineers and economists who design and implement decision support systems in practice. It also contains a sufficient number of examples to make it attractive to non-specialists.