Youth self-reports are a mainstay of delinquency assessment. However, making valid inferences about delinquency using these assessments requires equivalent measurement across groups of theoretical interest. We therefore examined whether a brief 10-item delinquency measure exhibited measurement invariance across non-Hispanic White (n=6064) and Black (n=1666) youth (ages 10-11 years old) in the Adolescent Brain Cognitive Development (ABCD) Study. We detected differential item functioning (DIF) in two items. Overall, Black youth were more likely to report being arrested or picked up by police than White youth of equivalent standing on the latent delinquency trait. Although multiple covariates (income, impulsivity, and callous-unemotional traits) reduced mean-level difference in overall delinquency, they had little effect on the DIF in the arrest item. However, the DIF in the arrest item was reduced in size and no longer significant after adjusting for neighborhood safety. Results illustrate the importance of considering measurement invariance when using self-reported delinquency scores to draw inferences about group differences, and the utility of measurement invariance analyses for identifying etiological mechanisms that may contribute to group differences.

Peer groups provide a critical developmental context in adolescence, and there are many well-documented associations between personality and peer behavior at this age. However, the precise nature and direction of these associations are difficult to determine as youth both select into and are influenced by their friends. We thus examined the phenotypic, genetic, and environmental links between antisocial and prosocial peer characteristics and several personality traits from middle childhood to late adolescence (ages 11, 14, and 17 years) in a longitudinal twin sample (N = 3762) using teacher ratings of personality, and self-reports of peer characteristics. At both within-person and between-person levels of analysis, less adaptive trait profiles (i.e., high negative emotionality, low conscientiousness, and low agreeableness) were associated with more antisocial and fewer prosocial peer characteristics. Associations between personality traits related to emotionality (negative emotionality and extraversion) and peer behavior were largely attributable to shared genetic influences, while associations between personality traits related to behavioral control (conscientiousness and agreeableness) and peer behavior were due to overlapping genetic and shared environmental influences. There was also some evidence for reciprocity and corresponsive processes such that traits in early adolescence contributed to selection into certain peer groups, which in turn extenuated those personality traits. Taken together, results suggest a set of environmental presses that push youth towards both behavioral undercontrol and antisocial peer affiliations, making the identification of such influences and their relative importance a critical avenue of future work.