This article builds on prior work and defines terms basic to the profession of occupational therapy. The prior work defined occupation as the relationship between occupational form and occupational performance and defined related terms, such as meaning, purpose, developmental structure, impact, and adaptation. This article shows how these terms relate to therapeutic occupation, a special type of occupation. Therapeutic occupation through occupational synthesis is the core of occupational therapy. Occupational synthesis is the design of the occupational form by the occupational therapist in collaboration with the recipient of services to advance therapeutic evaluation or achieve a therapeutic goal. Therapeutic occupation, then, is meaningful, purposeful occupational performance leading to assessment, adaptation, and compensation, all in the context of occupational synthesis. Finally, the idea of therapeutic occupation through occupational synthesis is related to frames of reference and models of practice in occupational therapy today.