The beliefs, assumptions, and expectations inherent in a program about the nature of the change brought about by program action and how it results in the intended improvement in social conditions. Program impact theory is causal theory; it describes a cause-and-effect sequence in which certain program activities are the instigating causes and certain social benefits are the effects they eventually produce.
US Environmental Protection Agency. (2007). Program Evaluation Glossary. Office of the Administrator/Office of Policy/Office of Strategic Environmental Management/Evaluation Support Division.