This second edition improves a number of DEA spreadsheet models and provides a DEAFrontier software for use with Excel 2007. Several new DEA models and approaches are added. For example, a new DEA-based supply chain model (chapter 8) and DEA models for two-stage processes (Chapter 14) are new additions to the book. Models with restricted multipliers are also discussed and added into the DEAFrontier software. A detailed use of sensitivity analysis in identifying critical measures under DEA is provided. A demonstration of how to use the DEAFrontier software is provided at the end of related chapters. Conventional and new DEA approaches are presented and discussed using Excel spreadsheets one of the most effective ways to analyze and evaluate decision alternatives. The user can easily develop and customize new DEA models based upon these spreadsheets. Spreadsheets are updated and modified for use with Excel 2007.