This book offers a guide for practitioners, researchers, and educators for the understanding and application of scientifically based evaluations that are both rigorous and flexible. The book covers seven major evaluation models and the author, a highly experienced academic and consultant evaluator, bridges the gap between theory and practice by illustrating the various approaches in simple language. The book explores the research evidence behind the utility of each model, shows how each approach looks in practice, and explains why it works for one situation and not another. Academically, the author is rooted in both education and public administration, areas that often share evaluation and needs assessment courses.