To advance evidence-based practice across rehabilitation professions, clinicians, and researchers could benefit from a structured way to clearly describe the treatment interventions used by their discipline. Development of the Rehabilitation Treatment Specification System is an interprofessional effort to use a theory-driven and systematic approach to define, specify, and quantify the complex nature of rehabilitation treatments. In this article, we introduce this novel approach and provide a case example that illustrates application to clinical practice. We invite occupational therapy practitioners to consider how clear specification of the content and process of their interventions could benefit practice, research, and education.