In a longitudinal study of 21 boys and 19 girls from infancy into adulthood, Englund, Levy, Hyson, and Sroufe (2000) found that children who were socially isolated during middle childhood had less self-confidence and were less socially competent with their peers in adolescence than those children who interacted with peers in middle childhood. In addition, children who were included socially in middle childhood were more likely to be self-confident and to hold leadership roles in adolescence than children with social difficulties in middle childhood (Englund, Levy, Hyson, & Sroufe, 2000).