["Journal of Personality, EarlyView. ", "\nABSTRACT\n\nObjective\nThis study investigated how autonomy support from close others influences Big five personality traits and subjective well‐being across young adulthood.\n\n\nMethod\nData were drawn from four six‐wave longitudinal studies spanning an eight‐month academic year, involving 1403 university students (Mage = 20.30, 85.60% female). Participants reported on autonomy support received from close others, personality traits, and subjective well‐being. Additionally, 406 close others provided external reports of the autonomy support they offered.\n\n\nResults\nAutonomy support was significantly related with increases in agreeableness, conscientiousness, and openness to experience, traits reflecting positive personality changes within the Big five framework. It also related to enhanced subjective well‐being. External reports corroborated participants' perceptions of autonomy support and their relations to outcomes.\n\n\nConclusions\nThese findings underscore the pivotal role of autonomy support from close others in enhancing personal growth during young adulthood. The results have important implications for clinical and relational contexts and contribute to a deeper understanding of the mechanisms linking autonomy support to well‐being.\n\n"]