The present study investigated prenatal and early postnatal risk factors associated with developmental patterns of disruptive behaviors (DBs; e.g., hyperactivity-impulsivity, noncompliance, physical aggression) from ages 1.5 to 5 years in a population birth cohort (N = 2,057; 50.7% boys). Six high-trajectory classes obtained by latent growth…

This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A 3-wave longitudinal actor-partner…

Using a sample of 767 children (403 girls, 364 boys), this study aimed to (a) identify groups with distinct trajectories of peer victimization over a 6-year period from primary school through the transition to secondary school, and (b) examine the associated personal (i.e., aggression or internalizing problems) and familial (family status,…

Several authors consider high and frequent conflicts between friends during childhood as a serious risk for subsequent conduct problems such as generalized physical aggression toward others (e.g., Kupersmidt, Burchinal, & Patterson, 1995; Sebanc, 2003). Although it seems logical to assume that friendship conflict could have some negative…

This study used a genetically controlled design to examine the direction and the magnitude of effects in the over-time associations between perceived relationship quality with mothers and adolescent maladjustment (i.e., depressive symptoms and delinquency). A total of 163 monozygotic (MZ) twins pairs (85 female pairs, 78 male pairs) completed…

Objective: This study aimed to identify the pathways through which a preventive intervention targeting young low-SES disruptive boys could result in lower crime involvement during adulthood. Method: The preventive intervention was implemented when the children were between 7 and 9 years and included three components (i.e. social skills, parental…

This study had three goals: (a) assessing the predictive association of externalizing and internalizing behaviors during childhood with sexual onset during early adolescence; (b) examining the interactive link of externalizing and internalizing behaviors with early sexual onset; and (c) investigating the moderating effect of gender in this…

This study examined the longitudinal link between clique membership status and the development of psychopathology in 451 children followed annually from age 9 to 12 years. Classroom clique membership status was identified through social network analysis, and internalizing and externalizing problems were assessed using peer nominations. Controlling…