Identifying predictors of classroom success is critical for supporting children's education. The first aim of the study was to examine whether infant attachment security positively predicts four cognitive outcomes among a high-risk sample of children: language skills, executive function, academic achievement, and cognitive ability. The second was to examine whether language skills and executive function in early childhood mediate the association between infant attachment and both academic achievement and cognitive ability in middle childhood. The study is relevant to a debate concerning whether cognitive outcomes can be predicted by early attachment security (e.g., Sroufe, 1988; Van IJzendoorn et al., 1995). Work showing an association between attachment and both language skills and executive function (e.g., Bernier et al., 2015; Van IJzendoorn et al., 1995) which have been shown to predict academic success (Duncan et al., 2007) provides the rationale for our predictions. The body of research examining infant attachment security as a predictor of cognitive outcomes has almost exclusively focused on low-risk samples. To address this, our sample included 149 mother-child dyads referred to Child Protective Services due to allegations of maltreatment. Attachment was measured at 24 months using the Strange Situation Paradigm (Ainsworth et al., 1978). Receptive language and executive function were assessed at approximately 48 months using the Peabody Picture Vocabulary Test (Dunn & Dunn, 1981) and the Dimensional Change Card Sort (Beck et al., 2011), respectively. Academic achievement and cognitive ability were measured using the Woodcock-Johnson III test battery at 9 years (Mather & Greg, 2001). Attachment security did not significantly predict any of the proposed outcomes. These results carry implications for the direction of future attachment research. Receptive language and executive function predicted both academic achievement and cognitive ability five years later. This carries implications for programs designed to support the education of at-risk children.