Showing how evaluation practice looks when guided by theory, the third edition of the influential "theory tree" book is significantly revised with over 80% new material, including a greater focus on equity and theories over theorists. Chapters from leading authorities describe the goals of each theory, the type of evaluation for which it is appropriate (formative, summary formative, summative, adaptive), the size of the program for which it is most applicable, specific prescriptions, and observable actions that help to define the theory. Readers are given the tools to select suitable approaches for the size, contexts and stage of an evaluation and their own personal values.