Coaching is an essential component of supporting teachers to implement evidence-based practices (EBPs) in classrooms. The Self-Determined Learning Model of Instruction (SDLMI), an EBP designed to promote student self-determination, uses a research-based coaching model with six guiding principles. This qualitative study analyzed the content of coaching conversations between coaches and general and special education high school teachers implementing the SDLMI with autistic students to explore alignment with the guiding principles of the SDLMI coaching model. Findings highlighted the usefulness of the coaching principles in building trust between coaches and teachers, supporting teachers to set meaningful goals and build skills and competencies related to SDLMI implementation, promoting innovation and fidelity, and facilitating reflective dialogue. Implications for research and practice are discussed. [This is the online first version of an article published in "The Journal of Special Education."]