Educators detect and intervene in a small proportion of bullying incidents. Although students are present when many bullying episodes occur, they are often reluctant to intervene. This study explored attributes of antibullying (AB) programs influencing the decision to intervene. Grade 5, 6, 7, and 8 students (N = 2,033) completed a discrete choice experiment examining the influence of 11 AB program attributes on the decision to intervene. Multilevel analysis revealed 6 latent classes. The Intensive Programming class (28.7%) thought students would intervene in schools with daily AB activities, 8 playground supervisors, mandatory reporting, and suspensions for perpetrators. A Minimal Programming class (10.3%), in contrast, thought monthly AB activities, 4 playground supervisors, discretionary reporting, and consequences limited to talking with teachers would motivate intervention. Membership in this class was linked to Grade 8, higher dispositional reactance, more reactance behavior, and more involvement as perpetrators. The remaining 4 classes were influenced by different combinations of these attributes. Students were more likely to intervene when isolated peers were included, other students intervened, and teachers responded quickly. Latent class analysis points to trade-offs in program design. Intensive programs that encourage intervention by students with little involvement as perpetrators may discourage intervention by those with greater involvement as perpetrators, high dispositional reactance, or more reactant behavior.