ObjectiveTo assess the impact of the Gender Roles, Equality and Transformations (GREAT) intervention: a narrative-based, resource-light, life-stage tailored intervention package designed to promote gender-equitable attitudes and behaviours, and improve sexual and reproductive health (SRH) and gender-based violence (GBV) outcomes among adolescents and their communities.DesignRepeated cross-sectional evaluation study, using propensity score matching combined with difference-in-difference estimation.SettingTwo postconflict communities in Lira and Amuru districts in Northern Uganda.ParticipantsMale and female unmarried adolescents (10–14 years, 15–19 years), married adolescents (15–19 years) and adults (over the age of 19 years) were selected using a stratified, two-stage cluster sample of primary and secondary schools and households (baseline: n=2464, endline: n=2449).Primary outcome measuresInequitable gender attitudes and behaviours; GBV; and SRH knowledge and behaviours.ResultsStatistically significant intervention effects were seen across all three outcomes—gender equity, GBV and SRH—among older and newly married adolescents and adults. Among older adolescents, intervention effects include shifts on: inequitable gender attitudes scale score: −4.2 points ((95% CI −7.1 to –1.4), p<0.05); Inequitable household roles scale score: −11.8 ((95% CI −15.6to –7.9), p<0.05); Inequitable attitudes towards GBV scale: −1.9 ((95% CI −5.0 to –0.2), p<0.05); per cent of boys who sexually assaulted a girl in past 3 months: −7.7 ((95% CI −13.1 to –2.3), p<0.05); inequitable SRH attitudes scale: −10.1 ((95% CI −12.9 to –7.3), p<0.05). Among married adolescents, intervention effects include shifts on: Inequitable household roles scale score: −6.5 ((95% CI −10.8 to –2.2), p<0.05); inequitable attitudes towards GBV scale: −4.7 ((95% CI −9.8 to –0.3), p<0.05); per cent who reacted violently to their partner: −15.7 ((95% CI −27.1 to –4.4), p<0.05); inequitable SRH attitudes scale: −12.9 ((95% CI −17.3 to –8.5), p<0.05).ConclusionThe GREAT intervention model demonstrates the promise of a resource-light, life-stage tailored programme that employs culturally appropriate, participatory and narrative-based techniques to advance gender equity and adolescent health. This type of programming contributes towards reductions in GBV and improved adolescent SRH outcomes.