Which came first, personality traits or identity processes during early and middle adolescence?

•The effects between personality and identity are bidirectional during adolescence.•The associations between personality and identity are complex at the facet level.•Developmental period impact on the associations between personality and identity.

No previous studies examined longitudinal associations between personality facets and identity dimensions in early and middle adolescence. To uncover these relationships, we test the direction of effects of domain- and facet-level personality traits with identity dimensions in early and middle adolescence. For this purpose, we used two annual waves of longitudinal data on 1233 Japanese early and middle adolescents. Cross-lagged models provided evidence for bidirectionality between personality and identity in early and middle adolescence. Moreover, our results highlighted that the relationships between the facets-level personality and identity dimensions were more complex than the associations between the domain-level of personality and identity dimensions. Our study facilitates a better understanding of the personality-identity interplay.