Self-perceptions of children from the integrated school sector in Northern Ireland were compared with those of children attending religiously segregated schools. In a cross-sectional study, the self-perceptions of 546 boys and girls aged 11-13 years and 14-15 years, at two integrated comprehensive and five segregated post-primary schools in Northern Ireland, were measured using the Self-Perception Profile for Children (Harter, 1985). The results of a School Type (2) x Year Group (3) x Gender (2) x Religion (2) MANCOVA, controlling for social class and ethos of schools, demonstrated a significant main effect for school type, with significant univariate effects favouring those at the integrated schools in the domains of physical appearance ( p < .01), social acceptance ( p < .01) global self-worth ( p < .05), and athletic competence ( p < .05). No evidence of a School Type x Year Group interaction suggests that these differences existed on entrance to the two types of school. A main effect for gender, favouring boys in physical appearance ( p < .001), athletic competence ( p < .05), and global self-worth ( p < .05), and girls on behavioural conduct ( p < .001), supported previous studies. Meanwhile, a post hoc analysis on the only significant interaction effect, for School Type x Religion, showed that Catholic adolescents from the integrated sector perceived themselves to be significantly more scholastically competent than those from the segregated sector ( p < .05). To further assess the development and stability of self-esteem among these adolescents, a long-term longitudinal study is indicated.