In this article, we describe the use of the objects and spaces of the physical environment by occupational therapy practitioners in the United States over the profession’s first 100 years. Using professional literature selected by decade from the years 1917 through 2016 to obtain data, we applied grounded theory methods to complete a detailed description. Team-based analysis over four coding schemes yielded a theoretical description of the profession’s therapeutic use of the physical environment. Study findings included descriptions across occupational therapy’s history of (1) treatment spaces, (2) the concepts of adapting and grading, and (3) a typology of constructive and nonconstructive applications of objects and activities by occupational therapy clients and practitioners. This extended historical perspective on trajectories of change in intervention space, the role of physical products in intervention, therapist repertoire, and the enduring role of adaptation suggests how the physical environment may be used in future practice.