In this comprehensive overview of the state-of-the-art in the field, group workers and social scientists explore group research issues. Learn how they grapple with the major problems associated with doing research on treatment groups. While discussing the outcomes of their group treatment programs, the authors address such issues as non-random assignment, impact of group process on outcome, retrospective research design, the unit of analysis, multivariate analysis, single-case designs, and small samples. Each insightful chapter illustrates the decisions and compromises that researchers must make to explore group phenomenon and treatment.