This study examined the antecedents of preschool age children's mental representations of attachment, assessed using the Attachment Story Completion Task (ASCT). Antecedent predictors were maternal attachment scripts, assessed using the Attachment Script Assessment (ASA), and the child's secure base behaviors, assessed using the Attachment Q-Set (AQS). Participants were 121 mothers and their preschool children assessed in three samples (Portuguese sample, n = 31; US Midwestern sample, n = 38; US Southeastern sample, n = 52). AQS and ASA assessments were completed approximately 1.5 years before the ASCT data were collected. No cross-sample contrasts for the attachment variables were significant. Correlations and structural equation modeling (SEM) indicated that the three attachment measures were significantly associated and that both maternal secure base script knowledge and children's secure base behaviors (AQS) were uniquely and significantly associated with children's mental representations of attachment (ASCT). A test of the indirect effect between maternal scripts and child representations through children's secure base behaviors was not significant.