The Craniofacial Collaboration United Kingdom (CC-UK) was established across the 4 Highly Specialized Craniofacial Centres (HSCCs) in the UK in 2015. This is the first wave of data to be analyzed, looking at 3-year-old children with sagittal synostosis who have had primary corrective surgery. This is a comprehensive, homogenous dataset, looking at parental measures of development and behavior. The results indicate that the majority of children are rated by their parents as falling within one standard deviation of the mean for both developmental and behavioral measures. However, there was a trend across the age groups within the sample which, although not statistically significant, indicates that more developmental difficulties may become apparent as children get older. Behavior was rated as more problematic, and the areas of greatest parental concern were Conduct (challenging or confrontational behavior) and Hyperactivity domains, where 24% of children were rated as within the clinically significant range. Although the majority of children were rated as falling within the average range, the difference in the mean between the sagittal and the normative group was significant in 5 of the 6 behavioral domains. Further research is required to examine whether these findings are stable over time and to look at the mechanism which might be driving these changes. It is anticipated that future CC-UK analysis will elucidate this more clearly.