To examine associations between insufficient sleep and neurobehavioral functioning in childhood as reported by mothers and teachers. Participants were 1046 children in a prebirth cohort study. Main exposures were insufficient sleep durations at 3 time points: 6 months to 2 years, defined as sleep <11 h/d, 11 to <12 h/d (vs ≥12); 3 to 4 years, defined as sleep <10 h/d, 10 to <11 h/d (vs ≥11); and 5 to 7 years, sleep <9 h/d, 9 to <10 h/d (vs ≥10). Outcomes at age 7 years were executive function, behavior, and social-emotional functioning, assessed using the Behavioral Rating Inventory of Executive Function (BRIEF) and the Strengths and Difficulties Questionnaire (SDQ). Higher scores indicate poorer functioning. Mothers and teachers completed both instruments independently. At age 7 years, mean (SD) mother and teacher report of the BRIEF global executive composite scale were 48.3 (7.9) and 50.7 (9.4) points, respectively, and of the SDQ total difficulties score was 6.5 (4.7) and 6.2 (5.7). In multivariable models, children who slept <10 h/d at 3 to 4 years had worse maternal-reported scores for the BRIEF (2.11 points; 95% confidence interval, 0.17-4.05) and SDQ (1.91 points; 95% confidence interval, 0.78-3.05) than those with age-appropriate sleep. Children who slept <9 h/d at 5 to 7 years also had worse scores. At both ages, associations with teacher-reported results were consistent with those of mothers. Infants who slept 11 to <12 h/d had higher teacher- but not mother-reported scores. Insufficient sleep in the preschool and early school years is associated with poorer mother- and teacher-reported neurobehavioral processes in midchildhood.