Background <p>A growing literature has examined the reward positivity (RewP), an event-related potential indicator of reward sensitivity, to social feedback. Research has indicated that a larger RewP to social rejection is associated with multiple internalizing problems, including anxiety, depression, and borderline personality. However, it is not clear whether the similar relationships are due to higher-order transdiagnostic dimensions of psychopathology.</p> Methods <p>A total of 222 participants, 18 to 35&#xa0;years (mean [<i>M</i>] = 23.06, standard deviation [<i>SD</i>] = 3.82; 86% assigned sex female), who were oversampled for psychopathology completed two social feedback tasks while electroencephalography was recorded to measure the RewP to social like (i.e., acceptance) and dislike (i.e., rejection) feedback. Participants also completed a self-report measure of pathological personality traits relevant to internalizing disorders, which was used to estimate a hierarchical model of internalizing psychopathology. We calculated direct, indirect, and total effects of the RewPs to social like and dislike feedback on higher-order (i.e., negative emotionality) and lower-order (i.e., traits) psychopathology.</p> Results <p>The results indicated a positive direct effect of the social dislike RewP on higher-order negative emotionality. There were several positive indirect effects of the social dislike RewP on maladaptive traits. The social like RewP did not show any direct or indirect associations with negative emotionality or traits.</p> Conclusions <p>The present study suggests that a larger neural response to social rejection is associated with greater higher-order negative emotionality. The RewP to negative social feedback may serve as a transdiagnostic marker of altered social information processing across internalizing disorders.</p>