The Preventing Relational Aggression in Schools Everyday (PRAISE) Program is a school-based program that has shown promise for reducing aggression. PRAISE, 20-session classroom-based universal prevention program, was designed to be appropriate and responsive to the needs of youth within the urban school context. A preliminary trial of PRAISE evinced positive effects for girls but was less effective for boys. Following the trial, the PRAISE program was adapted to enhance its impact for boys while maintaining its impact for girls. The current paper describes the changes and a new 3-school trial of the PRAISE program that examines its impact on subgroups. Results indicate that girls in PRAISE classrooms showed improvements in knowledge of social problem-solving strategies (SIP), reductions in hostile attributions (HAB), decreases in relational aggression, and suppression of overt aggression. Boys in PRAISE classrooms showed decreases in relational aggression and improvements in academic engagement, but no improvement in knowledge of SIP or HAB. Pooled analyses comparing boys' results from the initial trial and the current trial showed significant improvements in relational aggression and relational HAB with no differences in overt aggression, overt HAB, or SIP knowledge. Taken together, this iterative adaptation of PRAISE overcame many subgroup differences in program effects.