Effective professional development (PD) interventions that promote high quality teacher-child interactions are important mechanisms to support social-emotional and cognitive development in early childhood. One PD intervention that has shown to be effective is MyTeachingPartner (MTP); however, previous research has suggested that both teacher and contextual factors may moderate the effectiveness of PD interventions like MTP. In the current study, we used a self-determination theoretical (SDT) framework to identify subgroups of teachers (N = 401) through latent class analysis based on the fulfillment of their three basic needs: competence, autonomy, and relatedness. We found three latent classes of teachers: 1) Unconfident and Unsupported; 2) Unconfident but Supported; 3) Confident and Supported. We tested the effect of MTP, latent class membership, and the MTP by latent class interaction on the quality of teacher emotional and instructional support to identify which teachers benefitted most from the MTP intervention. While MTP benefitted teachers on emotional support similarly across classes, MTP was most effective for instructional support for teachers from the Confident and Supported class. As these were the only teachers who had all their basic needs met our results suggest teacher and contextual factors in concert are important in optimizing the effectiveness of PD.