The present study examined the longitudinal associations among birth weight status, maternal warmth, and children's cognitive competence within an at-risk sample (N = 1809) drawn from the Fragile Families and Child Wellbeing study. Of particular interest was whether birth weight moderated the associations between maternal warmth and indicators of cognitive competence. Birth weight and prenatal data were collected from medical records. Maternal warmth was assessed at ages 3 and 5. Cognitive competence was modelled as a latent variable representing standardized assessments of receptive vocabulary, reading, and math achievement. Overall, findings suggest that low birth weight (LBW) was significantly associated with cognitive competence at age 9. Results also indicated that birth weight moderated the longitudinal association between maternal warmth and cognitive competence. These results highlight the significance of birth weight and positive parenting for cognitive competence in middle childhood. The implications of these findings are discussed for interventions targeting LBW children.