Program theory evaluation (PTE) consists of an explicit theory or model of how the program causes the intended outcomes and an evaluation partly guided by this model. It is said to contain two critical components, a conceptual and an empirical. The purpose of an evaluation, in some PTEs, is to test the program theory; what it is about the program that causes the outcomes. Theory testing PTEs fight with the issue of casual attribution. In this book, the range of activity, considered program theory evaluation, was outlined and the major issues in theory and practice were identified and discussed more thoroughly. This volume was divided into two parts, Part One--Challenges in Practice and Part Two--Opportunities. Part One included four chapters that addressed some of the challenges in program theory, such as performance measurement, organizational learning, collarborative and participatory research, and meta-analysis. The challenges in implementing program theory in evaluation practice were reviewed with a major issue for evaluators being causal inference in PTEs. There are also challenges in deciding the types of program theories or models to test with an evaluation. Examples were provided on how evaluators developed more realistic causal models, noting that complexity was not a goal. Part Two consisted of five chapters exploring the potential for program theory to make contributions in evaluation’s future direction. In the advent of meta-analysis, evaluators were asked to make sense of multiple evaluations and pushed to improve their own studies for further review. Program theory was seen as helping evaluators meet some of the new challenges they faced. It was suggested that the strength of program theory was dependent on the substantive knowledge of the field. The development of a strong program theory would and should be the responsibility or program planners not evaluators. References and index