This article describes a 2-systems model that explains social behavior as a joint function of reflective and impulsive processes. In particular, it is assumed that social behavior is controlled by 2 interacting systems that follow different operating principles. The reflective system generates behavioral decisions that are based on knowledge about facts and values, whereas the impulsive system elicits behavior through associative links and motivational orientations. The proposed model describes how the 2 systems interact at various stages of processing, and how their outputs may determine behavior in a synergistic or antagonistic fashion. It extends previous models by integrating motivational components that allow more precise predictions of behavior. The implications of this reflective-impulsive model are applied to various phenomena from social psychology and beyond. Extending previous dual-process accounts, this model is not limited to specific domains of mental functioning and attempts to integrate cognitive, motivational, and behavioral mechanisms.In the history of attempts to discover the causes of human behavior, the most widespread explanations are based on the assumption that human beings do what they believe is good for them. Thus, they are construed as "rational animals" capable of recognizing the value or utility of their actions.At the same time, however, it is obvious that human beings do not always act this way; that is, under certain circumstances people behave in ways that do not reflect their values. To account for this phenomenon, to which the Greek philosophers gave the name akrasia (e.g., Mele, 1992), several strategies have been pursued. The first strategy assumes ignorance or lack of knowledge on the part of the actor. Socrates, for example, claimed that if people only knew what is good for them, they would act accordingly. A similar position is held by modern economists who imply that irrational decisions reflect a lack of appropriate information (Friedman, 1976). The second strategy postulates more than one set of principles that may control human action. For example, a behavior may occur mindlessly (Langer, Blank, & Chanowitz, 1978) or automatically; that is, without directing much attention to the utility of an outcome, a person may act the way he or she has acted many times before. Such habitual behaviors were the focus of many psychological theories in which the frequency and recency of previous executions of a given behavior were seen as primary determinants (e.g., Hull, 1943). The third strategy has been to understand human behavior as a function of drives. In particular, basic needs that are biologically rooted, such as hunger, thirst, or reproduction, are seen as major forces. Their strength may override considerations of utility and determine behavior in an immediate fashion.Although most psychological theories have focused on one of these aspects, some have acknowledged that behaviors may be multiply determined. Most prominently, Freud (e.g., 1933/1949 described human behavior ...