The purpose of this study was to examine the influence of a professional development (PD) program on teachers' implementation of the Teaching Personal and Social Responsibility (TPSR) model, and to identify the characteristics of PD that influence teaching practice. The participants were six elementary school teachers and 12 students, and the data were collected from interviews with the teachers and students, observations, and teachers' reflective journal entries. The findings revealed that PD enhanced the fidelity of implementation in terms of improving structural adherence, facilitating coherent instructional delivery, and making the students more active and responsible. The PD also helped the teachers to adapt the model by developing cultural differentiation strategies, modifying existing components, and extending the implementation of the TPSR through connection with other subjects or activities. The teachers found that the PD facilitated their implementation of TPSR by giving them common goals, empowering them as creators of knowledge, and providing a continuous and authentic learning experience.