In this paper, I describe the development of the Irie Classroom Toolbox, a school-based violence prevention, teacher training program for use with children aged 3-6 years. In-depth interviews were conducted with Jamaican preschool teachers, who had participated in a trial of a classroom behavior management program, at posttest (n = 35) and 5 years later (n = 20). An on-going process evaluation was also conducted. Teachers' preferred behavior management strategies and training methods were documented, and enablers and barriers to implementation were identified. Teachers were most likely to adopt strategies that they liked, found easy to use, and were effective. These included paying attention to positive behavior and explicitly teaching children the expected behavior. Teachers preferred active, hands-on training strategies based on social-cognitive theories. Enablers to intervention implementation included positive teacher-facilitator relationships, choice, collaborative problem solving, teachers recognizing benefits of the intervention, group support, and provision of materials. Barriers to intervention implementation were also identified. These data were integrated with behavior change theory (i.e., the behavior change wheel and theoretical domains framework) to develop an intervention grounded in common core elements of evidence-based programs while also utilizing teachers' perspectives. The resulting program is a low cost, adaptable intervention that should be suitable for training preschool teachers in other low-resource settings. (author abstract)