Occupational therapy practice has bridged two contradictory value systems for more than 100 years. This article describes the origins of practice ideas in both the United States and Britain and demonstrates that founding members of the occupational therapy profession all shared a core of humanistic beliefs while embracing the emerging paradigm of scientific medicine. The result has been an intellectual tension between the biological and the psychosocial aspects of practice. For more than 75 years, occupational therapists struggled to balance the art and science of patient care; recent debates on modalities, practice domains, and research priorities indicate that the unifying core of the profession is occupation that considers a person’s mind and body.