Background/Objectives. Despite advances in the treatment of sickle cell disease (SCD), cerebrovascular and cognitive consequences can be lifelong. Hematopoietic cell transplantation (HCT) is an established curative therapy and recent studies have demonstrated efficacy with reduced toxicity nonmyeloblative (NMA) regimens, but little is known about neuropsychological outcomes. The objective of this study was to describe neuropsychological, behavioral, and quality of life outcomes with medical correlates in children with SCD who received an NMA matched sibling donor (MSD) HCT. Design/Methods. This retrospective cohort analysis of nine patients with hemoglobin SS SCD underwent MSD HCT using the National Institutes of Health (NIH) NMA protocol. Results. Mean full scale intellectual functioning (FSIQ) was average pre-HCT (FSIQ=92.1, SD 9.0; n=8) and 2 years post-HCT (mean FSIQ=96.6; SD 11.1; N=9). Neuropsychological functioning was largely average across all cognitive domains. Moderate improvements were seen in processing speed and verbal memory (Cohen’s d=0.50-0.57) post-HCT, and declines occurred in measures of attention and fine motor speed and dexterity (Cohen’s d=0.70-0.81). Parents reported improved quality of life (Cohen’s d=0.91), less impact of SCD on their family, and less worry about their child’s future (Cohen’s d=1.44). Exploratory analysis showed relationships between pre-HCT hemoglobin (r=0.74, p<0.05) and creatinine (r=-0.75, p<0.01) with cognitive functioning, and a positive relationship between processing speed and time post-HCT (r=0.73). Conclusion. Neuropsychological functioning in a sample of children and adolescents treated identically with NMA MSD HCT remained stable or improved in most cognitive domains, and improvements in quality of life and family functioning were observed.