This study investigated attitudes toward restrictive gender norms among adolescents in Côte d'Ivoire and Sierra Leone (pooled N = 1,793, M[subscript age(baseline)] = 10.3, M[subscript age(follow-up)] = 11.6, 50% boys/girls). We examined individual and contextual predictors of gender attitudes, assessed change in gender attitudes over 2 years, and estimated the effect of a community-based norms diffusion intervention. Multiple regression analyses revealed that being a boy, exposure to violence against women, and restrictive norms among same-gender peers predicted support for a patriarchal division of adult roles, lower educational status for girls, and acceptance of gender-based violence. In contrast to evidence from Western contexts, we found limited evidence of increased flexibility in gender attitudes during early adolescence. However, the intervention significantly reduced support for restrictive gender norms, especially among boys. Findings reveal novel pathways through which young adolescents acquire beliefs about gender, and provide encouraging evidence regarding community-based approaches to shifting adolescents' gender attitudes.