This is an introduction to a set of four papers in the field of evaluation research. A main theme in these papers is the recognition that evaluation research is not a pure objective scientific self-standing activity, but one that interacts within a context and is influenced by the interchanges. (LMO)

This essay focuses on a key change that the author has experienced in the practice of program evaluation research over the past 20 years: the accommodation of the logic of science and the psychology of politics. This change has substantially altered the role of the evaluator, the evaluator's relationship with clients, the design of an evaluation…