This preregistered three-wave longitudinal study examined 1) how family functioning relates to identity commitments over time and 2) how identity commitments impact later school adjustment among 3) immigrant-origin (N=205, Mage=16.25 years, 31.1% girls) and native adolescents (N=480, Mage=15.73 years, 47.9% girls). Random Intercept Cross-Lagged Panel Models revealed significant positive between-person associations that were similar across both groups: Adolescents who reported higher family functioning also reported stronger identity commitments; and higher family functioning and stronger identity commitments were associated with higher school adjustment. However, some within-person associations differed across groups: Identity commitments related to less school adjustment among immigrant-origin adolescents, but were associated with more school adjustment among native adolescents over time, with important implications for future life chances.