Experimental evaluations make an important contribution to understanding the effectiveness of policies and programs, both within criminal justice and outside it. However, it is important to link experiments with articulating and assessing underlying program or policy theory. A clear link between theory and experiment is important. Challenges facing future work in the evaluation of criminal justice programs are first a better integration of activities focused on reconstructing and testing program theories on the one hand and experimental evaluations on the other. A second challenge concerns the quality of data collection suggesting a multi-method approach. The third and final challenge concerns the role of evaluations within the public sector. Public managers must expect to be evaluated. Managers of prisons, government departments, youth prevention organizations, and the like have a duty to provide evaluative information to the general public. This paper describes the general trends in evaluation in western societies, specifically its growth, characteristics, and developments outside western society. It concludes by outlining some of the challenges for future work in the evaluation of criminal justice programs. References