Sustainable Development Goal 5 challenges governments to address child marriage, which may inhibit girls from developing an agentic self. This paper assesses the direct influence of community gender norms on adolescent agency, and the normative contexts in which gender gaps in adolescent agency are larger or smaller in Nepal. Using baseline data for adolescent girls, adolescent boys, and adults in 54 clusters participating in the CARE Tipping Point Trial, multilevel analysis tested whether: adolescent boys had higher agency than girls; and community gender norms among adults "partly accounted for or modified" gender gaps in adolescent agency. Gender gaps in agency disfavoring girls were common. Community gender norms were more positively associated with intrinsic agency among girls than boys, and more negatively associated with instrumental and collective agency among girls than boys. Enhancing girls' agency while promoting gender-equitable community norms may empower girls' transition to adulthood.