This chapter traces the historical development of mathematical models of Pavlovian conditioning, one of the most fundamental and most studied forms of learning, highlighting impactful advancements from early to contemporary approaches. We examine how qualitative theories evolved into mathematical instantiations that were built on each other to describe experimental findings and quantitative predictions. The chapter covers models addressing competition between multiple stimuli, the role of temporal dynamics, and individual differences in conditioned responses. We discuss how applied behavior analysts may use these models to guide behavioral modification in therapeutic settings, providing concrete examples for interventions in a variety of conditions. We discuss outstanding issues like the challenge of mapping associative values to responding, which would make the models more precise and thus distinguishable. We conclude that mathematical models provide essential tools for understanding learning mechanisms and for developing evidence-based interventions, while acknowledging that diverse areas require further theoretical development.