Aggression toward peers who are perceived as weaker or different is a widespread problem for middle school students including those attending Catholic middle schools. Middle school students' normative beliefs about the acceptability of various types of aggressive behavior influences their own potential involvement in bullying. Therefore, how middle schoolers decide to respond to situations of peer aggression may affect their standing as either victims, bystanders to bullies, or as bully-victims in school environments over time. This study looks at how middle schoolers (sixth, seventh, and eighth grade girls and boys) in Catholic schools think it best to respond to peer aggression by examining their decision-making preferences for how targeted peers (from a vulnerable group) should respond to physical, verbal, or cyber aggression situations. Although significant effects regarding gender, grade, and type of peer aggression were found for the decision-making of the middle schoolers, findings reveal that overall middle schoolers' preferences were well developed for resisting peer aggression. The study provides important insights for how to supplement commonly existing curricula on social emotional learning in Catholic Schools with decision-making training inputs for the design of future school-based bullying prevention programs. Preparing middle schoolers in Catholic schools to respond to stop peer aggression in a proactive way supports the mission of Catholic schools to create safe and caring school environments.