A founder of the National Society for the Promotion of Occupational Therapy, Thomas Bessell Kidner (1866–1932) played a prominent role in the early development of occupational therapy in Canada and the United States. We describe Kidner’s early life and how his work using occupations evolved. We then examine ideas and assumptions about occupations as treatment and trace Kidner’s involvement through to his leadership role within the American Occupational Therapy Association. Through our analysis of primary and secondary source materials, we have extracted recurring themes and related them across and within the materials to discern Kidner’s influence on the profession. From among his many contributions, three areas emerge as particularly relevant to current practice: occupational therapy’s role in return to work, relationships with medicine, and the profession’s image. Kidner’s story gives us a window on our history and an opportunity to see how the profession has evolved.