The American Evaluation Association (AEA) board of directors formed a task force to create the AEA Guiding Principles for Evaluators in November 1992. The task force developed a set of guiding principles for evaluators and then saw those principles through the many steps that eventually resulted in their adoption by vote of the membership of AEA. The present volume documents and critiques those principles. It first records the history of task force efforts, with special attention to the most important conceptual issues that arose. Then, after presenting the principles themselves, the authors discuss and critique both the strengths and weaknesses of the Guiding Principles for Evaluators. These chapters fall into two categories: discussions at a very general level about the role of such principles in our profession, and problems that will arise in applying the principles in practice. The volume ends with a look to the future, to the sorts of issues and activities that we should keep in mind for the continued use and development of these principles.