The theory of Pavlovian conditioning presented by Robert Rescorla and Allan Wagner in 1972 (the Rescorla-Wagner model) has been enormously important in animal learning research. It also has been applied in a variety of areas other than animal learning. We summarize the contribution of the Rescorla-Wagner model to research in verbal learning, social psychology, human category learning, human judgments of correlational relationships, transitive inference, color aftereffects, and physiological regulation. We conclude that there have been few models in experimental psychology as influential as the Rescorla-Wagner model.The late 1960s was an exciting time for investigators of basic associative processes. Challenges to the view that pairing was sufficient to establish an association between events were coming from many quarters. Robert Rescorla, a new PhD from the University ofPennsylvania, published his influential paper suggesting that the contingency (or correlation) between events, rather than contiguity (or pairing), was the crucial factor in establishing associations (Rescorla, 1967). Leon Kamin, at McMaster University, reported a new phenomenon, "blocking," and rediscovered an old one, "overshadowing," both ofwhich were further demonstrations that a simple pairing analysis of classical conditioning was apparently inadequate (Kamin, 1968). Allan Wagner and colleagues, at Yale University, reported another phenomenon, "cue validity," that made essentially the same point: There are conditions under which conditional and unconditional stimuli (CSs and UCSs) are paired, but apparently little is learned about the relationship between them (Wagner, Logan, Haberlandt, & Price, 1968).Rescorla assumed a position at Yale University, where he collaborated with Wagner in the development of the model that integrated and made sense ofthese (and other) then-recent findings about Pavlovian conditioning. Rescoria and Wagner presented their model to Kamin and the other participants at a conference on classical conditioning that was held at McMaster University in May 1969. We now know that the attendees at that conference were present at the inauguration of an important era in conditioning research.