A computational model of sequence learning is described that is based on pairwise associations and generalization. Simulations by the model predicted that rats should learn a long monotonic pattern of food quantities better than a nonmonotonic pattern, as predicted by rule-learning theory, and that they should learn a short nonmonotonic pattern with highly discriminable elements better than 1 with less discriminable elements, as predicted by interitem association theory. In 2 other studies, the model also simulated behavioral "rule generalization," "extrapolation," and associative transfer data motivated by both rulelearning and associative perspectives. Although these simulations do not rule out the possibility that rats can use rule induction to learn serial patterns, they show that a simple associative model can account for the classical behavioral studies implicating rule learning in reward magnitude serial-pattern learning.One recurring question, almost a leitmotif in the study of comparative cognition, is how best to characterize complex animal behavior. Can a complex sequence of behavior through time, for example, be understood as a complex emanation of simple associative processes? Do putatively complex behaviors demand explanation in terms of higher order cognitive processes? Similarly, in the field of sequential learning, a fundamental question that is not yet fully answered is "What is learned in sequential learning?" In animal sequential-learning research, claims that animals chunk information and form hierarchical representations to facilitate sequential learning and memory (Dallal & Meck, 1990;Fountain, Henne, & Hulse, 1984;Macuda & Roberts, 1995;Roberts, 1979;Terrace, 1987) have inspired research designed to determine what processes mediate chunking and related phenomena. For example, serial-learning research has investigated a number of factors thought to affect how animals encode sequences of events (Ca-