School-based occupational therapists are well-equipped to prepare adolescents to transition from the education system to work and live in their communities, but they report challenges in securing their place on post-secondary transition planning teams. We argue that occupational therapists' efforts to advocate for their role in post-secondary transition could be strengthened by a deeper engagement with what is considered "best practice" in transition planning: improving students' ability and opportunity to exercise self-determination. In this commentary, we review the self-determination evidence-base; identify congruence between the underlying philosophies of self-determination and occupational therapy; and highlight gaps in existing self-determination models that occupational therapists are uniquely posed to fill by focusing on self-determination as they support transition age students.