Research in youth psychopathy has focused heavily on the affective features (i.e., callous-unemotional [CU] traits) given robust links to severe and chronic forms of externalizing behaviors. Recently, there have been calls to expand the scope of work in this area to examine the importance of other interpersonal (i.e., antagonism) and behavioral (i.e., disinhibition) features of psychopathy. In the present study, we apply an under-utilized statistical approach (i.e., dominance analysis) to assess the relative importance of CU traits, antagonism, and disinhibition in the prediction of externalizing behaviors in youth, cross-sectionally and at 9-month follow-up. Using a multi-informant (youth- and parent-report), multi-method (questionnaire, ecological momentary assessment [EMA]) preregistered approach in a diverse sample of clinically referred youth ( = 12.60 years, = .95 years, 47% female; 61% racial/ethnic minority), we found youth- and parent-reported psychopathy features accounted for a significant proportion of variance in externalizing behavior cross-sectionally and longitudinally. However, results provided limited support for our preregistered hypotheses. While antagonism and disinhibition had larger general dominance weights relative to CU traits for both youth- and parent-report, most differences were non-significant. Thus, the interpersonal, affective, and behavioral psychopathy features could not be distinguished from one another in terms of their importance in the prediction of externalizing behavior, assessed cross-sectionally or longitudinally. Taken together, the results highlight promising avenues for future research on the relative importance of youth psychopathy features.