Abstract This registered report evaluated the efficacy of an Italian adaptation of the "Identity Project," a school-based intervention promoting adolescents' cultural identity. Migration background and environmental sensitivity were explored as moderators. After adapting and piloting the intervention, a randomized controlled trial was conducted between October 2021 and January 2022 on 747 ethnically diverse adolescents (M[subscript age] = 15 years, 53% girls, 31% with migration background) attending 45 classrooms randomly assigned to the intervention or control condition. Bayesian analyses confirmed the efficacy of the Italian IP in enhancing exploration processes (Cohen's d = 0.18), whereas no cascading effect on resolution emerged. Youth with higher (vs. lower) levels of environmental sensitivity benefited more in terms of exploration. Implications for developmental theory and practice are discussed.