Duality models generally assume that human psychology is based on two separate systems of information processing. These systems have specific characteristics that differentiate them from one another. Such models are increasingly common in social psychology today. A selection of duality models is discussed and categorized according to three factors: the type of mental representation used in the specified processes (experiential vs. nonexperiential), the methods of processing (associative vs. propositional), and the differing degree of automaticity (based on the aspects of efficiency, awareness, intentionality, and controllability) of the processes. In addition, models' statements about the superiority of one process over the other are enumerated. Foundational models of attribution, stereotyping, persuasion, and more general models are explained in an overview. Central aspects of these foundational models are extracted and applied in a discussion of current duality models in general social psychology, as well as newer dual-process models of attitudes, moral judgments, and self-regulation. Models positing a process superior in information processing are contrasted with models positing two processes with different specializations in information processing, and the implications of improved integration and specialization are discussed.