According to constructivist theories, learning must be meaningful and actively engage students in decision-making and understanding. This study examined how the games for understanding (GFU) curriculum created a social constructivist learning environment that influenced eighth grade girls' levels of engagement within a sport based physical education program and identified pedagogical methods that assisted boys to value girls as participants and work to facilitate girls' engagement. Data consisted of teacher journal entries, student questionnaires, focus group interviews, co-teacher interview, and independent observations. Data were analyzed using open, axial, and selective coding. The findings suggested that cognitive aspects of the GFU environment actively engaged both boys and girls through small team activities. Shared responsibilities for team selection and peer coaching enabled students to become decisions-makers. Providing students with choices and minimizing competition helped girls feel supported. Likewise, modified games and ability groups helped boys value girls as participants and facilitate their engagement.