Who is most likely to join and engage in extreme political action? Although traditional theories have focused on situational factors or group identity, an emerging science illustrates that tendencies for extreme political action may also be rooted in individuals’ idiosyncratic cognitive and affective dispositions. This article synthesizes cutting-edge evidence demonstrating that individuals’ cognitive and affective architecture shapes their willingness to support ideological violence. In the cognitive domain, traits such as cognitive rigidity, slow perceptual strategies, and poor executive functions are linked to heightened endorsement for ideological violence. In the emotion domain, characteristics associated with emotional reactivity and impaired emotional regulation, such as sensation seeking and impulsivity, can facilitate readiness for extreme political action. The review homes in on the roles of cognitive rigidity and sensation seeking as traits heightening proclivities for extreme pro-group behavior and recommends that future research should assess cognition-emotion interactions to reveal different subprofiles of political actors. A theoretical framework focused on cognitive and affective information-processing traits—and their interactions—opens up tractable empirical questions and a future research agenda. Identifying subsets of ideologues is an endeavor with potential to inform the design of evidence-based interventions aimed at reducing ideological extremism and fostering social understanding.