Abstract(#br)Purpose(#br)This study investigates the relationship between adolescent girls' agency and social norms regarding early marriage, girls' education, and nutrition in West Hararghe, Ethiopia.(#br)Methods(#br)We conducted a cross-sectional study involving adolescent girls aged between 13 and 17 years in 2016. A two-stage cluster sampling procedure was followed to identify eligible respondents at the household level. A total of 114 clusters in four districts and 30 households from each cluster were randomly selected. Data were collected using a structured and pretested questionnaire. The agency composite score was measured based on 21 previously validated items. Descriptive and injunctive norm composite scores regarding education, marriage, and nutrition were constructed based on... context-relevant items. The weighted mean and standard errors were calculated for the agency and social norms composite scores. The relationship between girls' agency and descriptive and injunctive norms were examined using a multivariable linear regression model that accounted for a complex sample survey design.(#br)Results(#br)A total of 3,186 adolescent girls participated in this study. The multivariable linear regression analysis revealed that adolescent girls' agency score significantly and favorably associated with education (β = .19, p < .001), marriage (β = .13, p < .01), and nutrition (β = .20, p < .01) descriptive norms after adjusting for individual and household characteristics. Similarly, adolescent girls' agency was significantly and favorably associated with marriage (β = .21, p < .001) injunctive norms; however, positive injunctive norms around education (β = .09, p > .05) and nutrition (β = .12, p > .05) did not have a statistically significant association with girls' agency. The domains of agency scale related to the belief in women's health rights related to contraception use and the belief in women's right to refuse sex showed poor prosocial views.(#br)Conclusions(#br)Favorable descriptive and injunctive norms around marriage were significantly associated with greater adolescent girls' agency, which indicates the need to incorporate interventions that address social norms in efforts aimed to enhance adolescent girls' sexual and reproductive health status. Furthermore, attention should be given to monitor which domain of agency is improved by the interventions.