Evaluation of infants with craniosynostosis for surgical intervention, as opposed to conservative management, remains a challenge within the field of craniofacial surgery. Studies have consistently demonstrated that surgical repair of craniosynostosis is ideally performed between 3 and 12 months of age. As such, there is limited data regarding neurocognitive development in infants who initially present with uncorrected craniosynostosis after 12 months of age. Moreover, the impact of cranial vault surgery on neurocognitive development at all ages remains under investigation. A prospective, nonrandomized study was performed. All children with nonsyndromic craniosynostosis who presented for initial evaluation after 12 months of age were enrolled. The Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) was utilized to assess pre- and postoperative cognitive development and comparisons were made to normative values. Developmental delay is defined as scoring < 85. Five infants, average age 26 months (13–43 months) at initial presentation, underwent cranial vault remodeling and developmental testing. Fused cranial sutures involved: metopic (n = 4), and right coronal (n = 1). Cognitive testing demonstrated that 4 of 5 infants (80%) were developmentally delayed at presentation (scores: 60, 70, 72, and 80), and 1 infant was within normal limits (score: 100). Postoperative testing was performed between 2 and 12 months postoperatively. Universal improvement was observed in infants who were delayed prior to surgery (80, 80, 75, and 90, respectively). The infant who was not delayed prior to surgery remained within normal limits after surgery. This study demonstrates an association between cranial vault surgery and cognitive improvement in infants presenting late with developmental delay.