Emotion-based impulsivity has emerged as an important transdiagnostic risk factor for both internalizing and externalizing psychopathology. However, it is unclear how this dynamic process unfolds within individuals. We measured urgency within-persons as the momentary association between impulsivity and contemporaneous negative and positive affect in 4 ecological momentary assessment samples (N = 233[16,202 observations]; N = 302[11,360]; N = 311[17,517]; N = 291[20,297]) that span clinical, community, and student populations. Based on reflexive responding to emotion (RRE) and urgency frameworks, we hypothesized a) that significant individual differences in the dynamic association between affect and impulsivity would emerge, and b) that individual differences in positive and negative urgency pathways would be associated with externalizing and internalizing psychopathology. Within-person associations between negative affect and impulsivity consistently emerged; however, the association between positive affect and impulsivity was inconsistent across samples. Although average effects were small, significant individual differences existed in both urgency pathways. Consistent with prior studies, within-person urgency pathways were unassociated with global or dispositional measures of impulsivity. Contrary to expectation, within-person urgency was also unassociated with between-person measures of either internalizing or externalizing psychopathology. Yet, robust associations were seen between the same measures and average levels of momentary impulsivity and negative affect. We discuss results in terms of their relevance to both urgency and RRE frameworks and propose future directions to help disentangle emotion-based impulsivity and psychopathology in the moment. (PsycInfo Database Record (c) 2021 APA, all rights reserved).