This multimethod multisample longitudinal study examined how neurological substrates associated with goal directedness and information seeking are related to adolescents' identity. Self-reported data on goal-directedness were collected across three biannual waves in Study 1. Identity was measured one wave later. Study 1 design and measurements were repeated in Study 2 and extended with structural brain data (nucleus accumbens [NAcc] and prefrontal cortex gray matter volume [PFC]), collected across three biannual waves. Study 1 included 497 adolescents (Mage T1 = 13.03 years) and Study 2 included 131 adolescents (Mage T1 = 14.69 years). Using latent growth curve models, goal directedness, NAcc, and PFC volume predicted a stronger identity one wave later. These findings provide crucial new insights in the underlying neurobiological architecture of identity. [ABSTRACT FROM AUTHOR]