Rationale: Positive airway pressure therapy is frequently used to treat obstructive sleep apnea in children. However, it is not known whether positive airway pressure therapy results in improvements in the neurobehavioral abnormalities associated with childhood sleep apnea. Objectives: We hypothesized that positive airway pressure therapy would be associated with improvements in attention, sleepiness, behavior, and quality of life, and that changes would be associated with therapy adherence. Methods: Neurobehavioral assessments were performed at baseline and after 3 months of positive airway pressure therapy in a heterogeneous group of 52 children and adolescents. Measurements and Main Results: Adherence varied widely (mean use, 170 6 145 [SD] minutes per night). Positive airway pressure therapy was associated with significant improvements in attention deficits (P , 0.001); sleepiness on the Epworth Sleepiness Scale (P , 0.001); behavior (P , 0.001); and caregiver-(P ¼ 0.005) and child-(P , 0.001) reported quality of life. There was a significant correlation between the decrease in Epworth Sleepiness Scale at 3 months and adherence (r ¼ 0.411; P ¼ 0.006), but not between other behavioral outcomes and adherence. Behavioral factors also improved in the subset of children with developmental delays. Conclusions: These results indicate that, despite suboptimal adherence use, there was significant improvement in neurobehavioral function in children after 3 months of positive airway pressure therapy, even in developmentally delayed children. The implications for improved family, social, and school function are substantial. Clinical trial registered with www.clinicaltrials.gov (NCT 00458406).Keywords: continuous positive airway pressure; obstructive sleep apnea; sleepinessThe obstructive sleep apnea syndrome (OSAS) affects up to 4% of children (1). In most children, OSAS is associated with adenotonsillar hypertrophy, and improves after adenotonsillectomy (2). However, a significant proportion of children have residual OSAS postoperatively (3). Furthermore, many children with OSAS have other underlying conditions, such as obesity or Down syndrome. In these children, continuous positive airway pressure (CPAP) is usually used as the second line of treatment (2). Although CPAP is now being used commonly in children, only a handful of studies have evaluated its efficacy.If left untreated, OSAS may lead to substantial comorbidities. In particular, childhood OSAS has been shown to be associated with behavioral disturbances and learning deficits (4). The effect of PAP therapy in treating these neurobehavioral deficits in children is unknown. We therefore prospectively evaluated changes in neurobehavioral parameters, including symptoms of attentiondeficit/hyperactivity disorder (ADHD), sleepiness, behavior, and quality of life, at baseline and after 3 months of PAP in children with OSAS. We hypothesized that children treated effectively with PAP, including children with developmental delays, would show improvements in neurobehav...