Understanding the impacts of professional development (PD) on teachers' perceptions of their knowledge, skills, and usefulness (KSU) of evidence-based practices is important, particularly for self-determination interventions in inclusive, secondary classrooms. Limited research exists examining the impacts of self-determination intervention PD on teachers' learning outcomes. In this study, we analyzed the impacts of PD on the Self-Determined Learning Model of Instruction (SDLMI) delivered during a 3-year research project on trained teachers' self-reported KSU of self-determination. Results suggested there were positive impacts on teachers' KSU of self-determination after PD. Implications for future research and practice are discussed.