Behavioral momentum theory (BMT) represents one of the earliest quantitative models in the field of behavior analysis. With roots in work conducted on response persistence under primarily multiple reinforcement schedule arrangements, BMT provides an account for the impact of reinforcement histories on a behavior’s resistance to change. Much of the literature specific to BMT has shown this impact to be a function of Pavlovian contingencies, highlighting the role of context. Researchers have identified a number of specific variables related to reinforcement parameters affecting response persistence and shown the effects across a wide variety of reinforcement schedule disruptors. As well, the findings produced in the basic laboratory have been replicated and extended in translational and applied behavior analytic studies. While BMT provides a thorough account of response persistence under certain conditions, the model has some weaknesses that have led to the development of new quantitative models. This chapter provides an overview of the history of BMT, including relevant equations, demonstrations in basic and translational/applied laboratories, and a discussion of its weaknesses.