Holistic patient care and the scientific research method are two important aspects of occupational therapy. Bird T. Baldwin contributed to the formulation of these tenets at the beginning of this century. Baldwin, a psychologist by training, became the director of the occupational therapy department at Walter Reed General Hospital in Washington, DC, during World War I. In his department, functional rehabilitation was achieved via scientifically analyzed purposeful activities. He believed that purposeful activity was superior to exercise. Activity choice was based on physical, vocational, social, and emotional considerations. True to his scientific approach, Baldwin designed and adapted devices to provide standardized treatment protocols. Because Bird T. Baldwin’s approach to rehabilitation remains of value today, a review of his work is relevant to the occupational therapy community.