To better explain the near-universal association between peer and self-reported delinquency, three frameworks have been offered and have received varying degrees of support: (1) socialization or the social transmission of norms, attitudes, and behaviors among group members; (2) selection or the congregation of youth with similar traits and predispositions; and (3) enhancement or a combination of socialization and selection processes. Making use of sibling pairs and peer network data from the National Longitudinal Study of Adolescent to Adult Health, the current study compares all three frameworks using modified bivariate Cholesky models to simultaneously examine gene-environment correlations (rGE) and interactions (G × E). Findings revealed that peer deviance (as reported by peers themselves) moderated underlying influences on delinquency such that genetic influences decreased and environmental influences increased as peer deviance increased. While previous studies have reported additional patterns of moderation (e.g., increases in both genetic and environmental influences), such studies have relied on subjective measures of peer behavior, more restrictive measures of delinquency, and samples comprised of young children. The results revealed preliminary evidence in favor of the selection hypothesis, but the overall patterns of moderation stemming from the examined G × E fall in line more closely with the enhancement hypothesis of peer influence.