The use of occupation as a therapeutic method is the essence of the profession of occupational therapy. This core of therapeutic occupation is flexible across cultures, times, health care environments, and different philosophies of the nature of the human being. Given this adaptability, the profession espouses diverse models of practice--the multiple frames of reference that guide therapeutic occupation for different populations in different settings. Across the history of the profession, therapeutic occupation has been the common core of otherwise different approaches to intervention. Although each of the many past and current models of practice has a different viewpoint, the common factor is the synthesis of occupational forms designed to elicit meaningful and purposeful occupational performance. Occupational synthesis is the essential act of the occupational therapist. It is necessary that occupational therapists confirm the power of therapeutic occupation through research that examines the profession's central principles. Occupational therapists are also urged to use the term occupation consistently and proudly in their interactions with recipients of therapy, fellow health care professionals, and each other. The profession of occupational therapy will flourish because occupation, its core, is so basic to human health yet so flexible, depending on the needs of the individual human being.