The situational factors precipitating anger and reactive (i.e., emotional) aggression have been well documented in the social psychology literature. However, there are pronounced individual differences in reactivity to hostile cues that are equally important in understanding such outcomes. Indeed, in predicting tendencies toward anger and reactive aggression, it appears critical to simultaneously consider both individual difference and situational factors. This case is first made. Subsequently, the utility of this individual difference realm in understanding wider personality processes related to social cognition, reactivity, and self-regulation is highlighted. Individual difference frameworks of this type are scattered across multiple literatures. For this reason, the present special section of the Journal of Personality invited contributions from experts in developmental, social, cognitive, trait, and biological subdisciplines of psychology. The final section introduces the invited papers and makes a brief case for broader process-related conclusions that are generally apparent.