Background The purpose of this study was to confirm initial reports of elevated behavior problems in children with single-suture craniosynostosis (SSC), using multiple informants, longitudinal analyses and a control group. We hypothesized higher levels of maladjustment for children with SSC than comparison children, particularly at the older age and in selected areas of previously observed vulnerability: attention and social adjustment. Method A Child Behavior Checklist (CBCL) was completed when children were ~19 months by 436 mothers (219 with SSC) and 371 fathers (177 with SSC); and at ~37 months by 361 mothers (175 with SSC) and 303 fathers (142 with SSC). A minimum of one caregiver/teacher report was available for 169 of these children (74 with SSC) using the Caregiver-Teacher Report Form (CTRF). Results Average CBCL/CTRF externalizing, internalizing and total scores for all informants were consistently higher (worse) for children with SSC than control group children, but most differences were small and statistically non-significant. No differences associated with suture site were found. At the oldest age point, both mothers and fathers (but not teachers) generated higher average scores for patients than for controls on scales measuring attention and social problems, with small to medium effects sizes (0.20 to 0.32). Conclusion On average toddlers/preschoolers with SSC show behavioral development that is largely indistinguishable from same-aged peers of similar socioeconomic background. The predictive significance of small group differences in attention and social adjustment will be assessed in a follow-up of this cohort at age 7.