Attachment representations are increasingly operationalized as secure base script knowledge—one’s level of awareness of the temporal-causal schema that summarizes basic features of seeking and receiving effective support from caregivers when in distress. A method was recently developed to assess secure base script knowledge during the Adult Attachment Interview (AAIsbs), though its predictive validity for mental health outcomes is largely unknown. A series of pre-registered analyses, leveraging two large, longitudinal cohorts to assess the associations between AAIsbs and depression in emerging adults revealed that higher AAIsbs at age 18 years in the normative-risk sample, but not in a higher-risk cohort, predicted fewer depressive symptoms at age 30 years. In general, these associations were robust to concurrent depressive symptoms, sociodemographic and cognitive functioning covariates, and other traditional attachment representation measures. Findings support the importance of considering schematic attachment representations in developing interventions to improve young adults’ well-being.