Using a sample of individuals (277 males, 315 females) studied since birth in the NICHD Study of Early Child Care and Youth Development, the present study investigated how early pubertal maturation and school transition alter youth trajectories of social competence during the transition to adolescence. Social competence showed strong continuity, with the most socially competent children remaining so in adolescence. Early pubertal maturation and school transitions accentuate individual differences, increasing social competence among more competent youth, but further diminishing social competence among less competent individuals. In essence, facing challenges that require social competence may further separate competent individuals from less competent peers. Thus, the psychosocially rich become richer, while the psychosocially poor become poorer.