In this paper, the authors describe the benefits and pitfalls of mixed methods designs. They argue that mixed methods designs may be preferred when evaluating professional development programs for p-K-12 education given the new call for accountability in making data-driven decisions. They summarize and critique the studies in terms of limitations of the studies, the measures utilized in the mixed methods design (quantitative and qualitative measures), and the overall analysis of the impact of this body of literature. Implications for researchers who want to apply mixed methods designs and evaluators who want to influence professional development planning will be outlined. (Contains 3 tables and 1 figure.)