A central assumption of identity theory is that adolescents reconsider current identity commitments and explore identity alternatives before they make new commitments in various identity domains (Erikson, 1968; Marcia, 1966). Yet, little empirical evidence is available on how commitment and exploration dynamics of identity formation affect each other across adolescence at the within-person level. Therefore, the current study (N = 494, Mage Time 1 = 13.3 years) examined reciprocal within-person longitudinal linkages between adolescents’ identity exploration and identity commitment making in the interpersonal and educational identity domains. For this purpose, we constructed a multilevel type cross-lagged panel model from early to late adolescence (i.e., across 5 successive years). Results supported Erikson’s (1968) hypothesis that adolescents reconsider current identity commitments and explore alternatives before they make strong commitments within the interpersonal identity domain across early to late adolescence. Within the educational identity domain, increasing identity commitment level and commitment fluctuations predicted less identity reconsideration over time. Our findings support identity theory, but indicate that the processes of identity formation might differ depending on the identity domain.