Based on a subsample (N = 673) of the NICHD Study of Early Child Care and Youth Development (SECCYD) cohort, this article reports data from a follow-up assessment at age 18 years on the antecedents of secure base script knowledge, as reflected in the ability to generate narratives in which attachment-related difficulties are recognized, competent help is provided, and the problem is resolved. Secure base script knowledge was (a) modestly to moderately correlated with more well-established assessments of adult attachment, (b) associated with mother-child attachment in the first 3 years of life and with observations of maternal and paternal sensitivity from childhood to adolescence, and (c) partially accounted for associations previously documented in the SECCYD cohort between early caregiving experiences and Adult Attachment Interview states of mind (Booth-LaForce & Roisman, 2014) as well as self-reported attachment styles (Fraley, Roisman, Booth-LaForce, Cox, & Holland, 2013). (PsycINFO Database Record (c) 2014 APA, all rights reserved).