“Program Evaluation” is a widely used research approach that helps answer questions about whether a program or intervention works, how it works, for whom it works, and under what circumstances it works. A program evaluation designed to answer one or more of these questions provides important information that can be used to improve, tailor, or scale a program. Knowing whether and how a program works can also help funders and policymakers know how to best allocate resources with the greatest chance of impact.

There are many different approaches or “designs” to program evaluation, each with its own strengths and limitations. This brief reviews the traditional “pre-post” design and the retrospective “pre-post” design.