The Total Performance System (TPS) concept, a conceptual tool to aid management of a wide variety of complex systems such as classrooms, courses, schools, and businesses is presented as a unit of analysis for systems approaches to educational and management problems. A description of the TPS concept defines the classroom as a processing system with inputs (students) and outputs (graduates), and an internal feedback loop to guide educational processes. That description is criticized as incomplete and an alternative total performance system is suggested which adds a receiving system (to receive the graduates and any other outputs) and an external feedback loop (to call attention to interactions between the classroom and its environment and to the ultimate validation and evaluation of internal feedback measurements by external feedback). Use of the TPS concept is illustrated through application to curriculum and organization development problems including data from a classroom management project utilizing the TPS concept. (Author)