Every program evaluation eventually arrives at the same question: did it work? Participant self-report is the most common way to answer it, but the design determines the credibility and trustworthiness of the resulting information. Three designs dominate practice: global ratings of change at program end, traditional pre-post, and retrospective pre-post. The first is the most vulnerable to bias. Both pre-post designs are more rigorous; the choice depends on what is being measu