The notion that different systems may determine human behavior has a long history in our discipline (e.g., Freud, 1933/ 1949. In modern psychology, this notion is reflected in numerous dual-system models in cognitive, personality, and social psychology (e.g., Epstein, 1990; Metcalfe&Mischel, 1999; Sloman, 1996; Smith & DeCoster, 2000; Strack & Deutsch, 2004). Even though different terminologies have been used to describe the two systems, these models share the general assumption that structurally different systems of information processing underlie the production of impulsive, largely automatic forms of behavior on the one hand and deliberate, largely controlled forms of behavior on the other. Some authors have also proposed that distinct brain areas may underlie these systems (e.g., Bechara, Noel, & Crone, 2006; Lieberman, 2007). All of these models are applicable to the study of self-control outcomes. Among these models, the reflective impulsive model (RIM; Strack & Deutsch, 2004) is particularly concerned with how the two systems compete to determine behavior (Strack & Deutsch, 2004). We therefore adopt the logic of the RIM to the study of self-control and use the labels impulsive and reflective to denote the two systems that are assumed to underlie behavior production, even though many of the predictions tested in the research review below could be made by other dual-system models as well.