Increasingly, researchers have operationalized AAI derived attachment representations as reflecting individual differences in secure base script knowledge (AAIsbs)—the degree to which individuals show awareness of the temporal-causal schema that summarizes the basic features of seeking and receiving effective support from caregivers when in distress. In a series of pre-registered analyses, we used AAI transcripts recently re-coded for AAIsbs and leveraged a new follow-up assessment of the NICHD Study of Early Child Care and Youth Development cohort around age 30 years (479 currently partnered participants) to assess and compare the links between AAIsbs and traditional AAI coding measures in late adolescence and self-reported romantic relationship quality in adulthood. Higher AAIsbs predicted better dyadic adjustment scores in adulthood, above and beyond other AAI-derived coding measures, and sociodemographic and cognitive functioning covariates. Findings extend previous evidence pointing to the predictive significance of AAIsbs for multiple adult functioning domains.