The Cognitive-Affective Processing Systems or CAPS theory (Mischel & Shoda, 1995) was proposed to account for the processes that explain why and how people's behavior varies stably across situations. Research on Rejection Sensitivity is reviewed as a programmatic attempt to illustrate how personality dispositions can be studied within the CAPS framework. This research reveals an if ... then ... (e.g., if situation X, he does A, but if situation Y, he does B) pattern of rejection sensitivity such that high rejection sensitive people's goal to prevent rejection can lead to accommodating behavior; yet, the failure to achieve this goal can lead to aggression, reactivity, and lack of self-concept clarity. These situation–behavior relations or personality signatures reflect a stable activation network of distinctive personality processing dynamics. These dynamics link fears and expectations of rejection, perceptions/attributions of rejection, and affective/behavioral overreactions to perceived rejection. Self-regulatory and attentional mechanisms may interact with these dynamics as buffers against high rejection sensitivity, illustrating how multiple processes within a CAPS network play out in behavior.