Clinicians and training programs strive to implement evidence‐based practices and manualized treatments with fidelity. However, the constraints of a local setting may limit the extent to which this is possible. In the current study, an adapted model of an evidence‐based social–emotional learning small group curriculum, the Incredible Years Children’s Small Group Training Series (Webster‐Stratton, 2004), was implemented and evaluated in an elementary school setting. Results of the study demonstrated statistically significant decreases in problem behaviors and intensity of problem behaviors, as rated by teachers. Teachers also reported improvement in classroom behavior, emotion regulation, problem‐solving, and friendship skills, as well as a high overall level of satisfaction with the intervention itself. Discussion of the results includes a review of the strengths and limitations associated with outcome research in a naturalistic setting, suggestions to consider when adapting evidence‐based programs, and recommendations for future research.

Evidence-based programs, such as bullying prevention, often demonstrate disappointing outcomes when widely disseminated. Engaging opinion leaders-those individuals whom others emulate and go to for advice-in the process of adaptation and implementation may improve outcomes. However, opinion leaders have the most influence on individuals who are similar to them, making social groups an important consideration in opinion leader recruitment. In a series of studies we examined the social groups of childhood and whether teacher nominations can be used to identify opinion leaders within these groups. In Study 1, students (N ¼ 35) and school staff members (N ¼ 23) reported on social groups at their school. Results suggest four predominant social groups (Elites, Athletes, Academic, and Deviants), and that students and adults are equally likely to identify these groups. In Study 2, students (N ¼ 29) and school staff members (N ¼ 10) identified opinion leaders from each of the four predominant social groups. Student and school staff members agreed on the primary opinion leader within the Elites, Athletes, and Academics groups, but identified different opinion leaders from