Unstructured playtime at school, such as recess and afterschool activities, is essential for children's social development but often becomes a setting for bullying. Despite effective bystander programs, research on students' willingness to intervene in these contexts remains limited. This cross-sectional study used mixed methods to investigate the factors influencing students' willingness to intervene in bullying during afterschool programs. Data were collected from 55 ethnically diverse students (31 girls and 24 boys) aged 8-12, attending Title I schools, through surveys and focus group interviews. Quantitative data indicated a high overall willingness to intervene, with girls and younger students significantly more likely to take action. Positive correlations were observed between intervention willingness and factors such as enjoyment of the program and three goals of personal and social responsibility. Furthermore, students with better self-management skills were more proactive in addressing bullying incidents. Focus group discussions revealed that those who felt a strong community and responsibility were more likely to intervene. Enhancing enjoyment, fostering strong peer connections, and promoting personal and social responsibility in afterschool programs can significantly increase students' willingness to intervene in bullying, offering valuable guidance for developing more effective anti-bullying strategies in playground settings.