Establishing a reference source for DEA, this text aims to accomplish the following seven objectives: motivate DEA as a new approach to organizing and analyzing data beyond its origin in efficiency analyses; present an integrated framework, and standardized notation for understanding basic DEA models and their extension; develop a deeper understanding of computational issues involved in solving various DEA formulations; provide insights into the DEA process, its usage and interpretations; highlight the range of potential uses of DEA through examples of novel applications; provide an updated bibliography; and to facilitate the diffusion of DEA by making Chapters 1-4 and 21 available for inclusion in operations research, econometric and statistic textbooks under normal provisions which maintain original copyright status.