Our study is a cross-sectional, descriptive study to evaluate the developmental outcome for school-age children with HLHS. The general approach of the proposed research is confirmatory study/hypothesis testing. The hypothesis (neurodevelopmental outcome of children with HLHS is inversely correlated with cerebral oximetry values as measured by NIRS in the 48 hours following the Norwood operation) was formulated based on a meticulous review of the literature, which clearly demonstrates a substantial prevalence of neurodevelopmental deficits in children with HLHS who have undergone surgical palliation. The methodologies for measuring developmental outcome are highly reproducible and have been validated in this population.