The U.S. Department of Energy's (DOE) Office of Energy Efficiency and Renewable Energy (EERE) is developing a theory-based approach to impact evaluation that could be used by its deployment programs for evaluating energy savings and market effects with credible attribution of impacts (DOE forthcoming). The purpose of this paper is to describe the framework and its research design. The framework also provides information for program improvement in a consistent and structured manner. It joins Everett Rogers' diffusion of innovation theory with logic models to examine linkages between program activities, target audiences, behavioral and institutional changes, and energy savings or adoption of cleaner energy sources. Using the framework's templates, a program can describe its outcome goals and program logic, as well as identify key outcome questions and indicators (metrics). Evaluators could use the framework to understand where to look within the program logic for measured outcomes such as sales or adopted technologies and practices. Finally, by using the framework a causal link between the program and outcomes can be tested and alternative explanations investigated.