The current study examined the concurrent and longitudinal relations among sleep problems with academic and psychosocial functioning in a prospective cohort study, the Tucson Children's Assessment of Sleep Apnea study (TuCASA). Children were assessed between the ages of 6 and 11 years and again approximately 5 years later. Sleep disordered breathing was assessed via polysomnography and sleep duration, sleep consistency, excessive daytime sleepiness (EDS), and insomnia symptoms were evaluated via parental and self-report. Although regression models for sleep problems yielded minimum effect sizes in predicting standardized achievement scores, they jointly related to lower parent-reported grades and adolescent-reported school problems. Additionally, hierarchical multiple regression revealed that sleep parameters significantly predicted measures of psychosocial functioning with medium (Behavior Assessment Scales [BASC-2] Parent Report Form [PRF]-Behavioral Symptoms Index, Internalizing Behaviors Composite; Self-Report of Personality [SRP] Emotional Symptoms Index, Internalizing Behaviors, Personal Adjustment Composite) to small-medium effect sizes (BASC-2 PRF Externalizing Problems, Adaptive Skills Composites, BASC-2 SRP Inattention/Hyperactivity Composite) above and beyond sociodemographics and IQ. Similar findings occurred for BASC-2 subscales. Parent-reported current EDS and youth-reported insomnia symptoms were the most consistent contributors. School psychologists should screen for and treat or make referrals for sleep problems, taking into account chronicity and multiple informants' perspectives, to maximize academic intervention benefits.