In this paper, we examine the link between evidence-based practice and social validity by describing five examples from our own research where social validity measures resulted in data that were essential to both a clinical and research agenda on evidence-based practice. Social validity data are reviewed in the context of behavioral skill training for family members of children with autism, the implementation of a manualized approach for treating severe problem behaviors, an intervention to increase play behaviors in young children with special needs, a home coaching intervention designed to reduce child challenging behaviors, and a large scale longitudinal study of early school failure. The examples illustrate the essential function of social validation and highlight implications for research and the future development of evidence-based practice. (Contains 2 tables and 4 figures.)