The purpose of this study was to evaluate the efficacy of a universal social skills program, the Social Skills Improvement System Classwide Intervention Program (SSIS-CIP; Elliott & Gresham, 2007), for students in first grade. Classrooms from 6 elementary schools were randomly assigned to treatment or business-as-usual control conditions. Teachers assigned to the treatment condition implemented the SSIS-CIP over a 12-week period. Students' social skills, problem behaviors, and approaches to learning were assessed via teacher ratings and direct observations of classroom behavior. In addition, their early literacy and numeracy skills were measured via computer-adaptive standardized tests. SSIS-CIP participation yielded small positive effects in students' social skills (particularly empathy and social engagement) and approaches to learning (academic motivation and engagement). Students' problem behaviors and academic skills, however, were unaffected by SSIS-CIP exposure.