This study explored the facilitating function of religion in the lives of adolescents, postulating that religiously involved students would endorse prosocial--rather than egoistical--values, and that their prosocial values would foster a sense of belongingness to their church, family, and school. Participating were 369 boys and 372 girls attending 3 Catholic high schools in Winnipeg, Canada. Subjects completed questionnaires assessing family religion, religiosity, prosocial values, school attitudes, family satisfaction, self-esteem, and life satisfaction. Findings indicated no sex differences in family religion, religiosity, school attitudes, family satisfaction, self- esteem, or life satisfaction. However, girls endorsed prosocial value much more than did boys. Religiosity was strongly related to prosocial values, good school attitudes, and family satisfaction. Compared to girls' religiosity, boys' religiosity was more predictive of the endorsement of prosocial values, good school attitudes, family satisfaction, self-esteem, and life satisfaction. Structure equation analyses strongly supported a social facilitation model of the role of religiosity in the lives of adolescents: religiosity fostered the endorsement of prosocial values, prosocial values enhanced social adjustment (school attitudes, family satisfaction), and good social adjustment contributed to good personal adjustment (self-esteem and life satisfaction). (Contains 29 references.) (KB)