This paper examined how group work researchers and practitioners have used single-case designs (SCDs) to evaluate interventions for improving group processes and outcomes. Fifty-one group work studies published from 1972 to 2012 using SCDs and addressing a wide range of problems were identified. The 8 types of SCDs applied in these studies are discussed in relation to their methodology, relative strengths and limitations, and applications in group work research and practice evaluation. Selected studies, which varied in quality and rigor, are described to illustrate design features and utility for group work. The review reveals the challenges and opportunities in using SCDs, and it provides recommendations for designs best suited to answer particular questions.