The third edition of this best-selling text in evaluation incorporates the experience that the authors gained from the many evaluations they have undertaken since the first edition. On more than one occasion they even found themselves on opposite sides of the table -- representing different agencies involved in a project.Evaluation has changed much in ten years, and this freshly-written edition reflects those changes: introduction of microcomputers; econometric modelling; political changes and much more. The authors have also made good use of comments from teachers and students who have used previous editions.Another important addition is the production of a companion Workbook written in conjunction with Professor Gary Sandefur of the University of Wisconsin. Taken together, the two volumes represent a comprehensive introduction to evaluation.