Deriving hypotheses from I³ theory (pronounced "I-cubed theory"), the authors conducted 4 studies to clarify the circumstances under which dispositional aggressiveness predicts intimate partner violence (IPV) perpetration. Consistent with the hypothesis that this link would be stronger when inhibitory processes are weak rather than strong, Studies 1 and 2 demonstrated that dispositional aggressiveness was an especially robust predictor of IPV perpetration among people experiencing self-regulatory strength depletion. Consistent with the hypothesis that this Dispositional Aggressiveness × Inhibition interaction effect would be stronger when instigating triggers are strong rather than weak, Studies 3 and 4 demonstrated that dispositional aggressiveness was an especially robust predictor of IPV perpetration among people characterized by both weak inhibition (poor executive control in Study 3, depletion in Study 4) and strong instigation (provocation in both studies). These effects were robust in studies employing experimental and nonexperimental designs, cross-sectional and longitudinal methods, dating and married participants, self-report and behavioral measures of IPV perpetration, and diverse operationalizations of all constructs. Discussion emphasizes the importance of incorporating instigating, impelling, and inhibiting processes into theoretical and empirical analyses of IPV perpetration.