Describing the ever-changing supply and demand for physical therapy personnel in the United States is an intricate, complex, and profoundly significant task for the profession. In this article, a review of data relating to the supply of physical therapy personnel in the work force and their typical career patterns is presented. The estimates of the numbers of physical therapists and physical therapist assistants are discussed, as are problems associated with such estimates. Studies of career patterns of physical therapists are compared. Changes in the participation rates of women in the physical therapy work force over the last three decades are described. Career expectations, defined as both length and pattern of work-force participation, of entering physical therapy professionals are presented. Strategies to adjust the work-force participation of personnel through changes in the educational process, career patterns, and practice patterns are discussed.