The design was that of a cohort study with a nested case control arm. Sleep disordered breathing was evaluated in 850 children with in-home state-of-the art respiratory monitoring techniques. A number of risk factors were evaluated: sociodemographic characteristics; anthropometry; upper and lower airway size and function (questionnaire, spirometry, and reflectometry); perinatal exposures (from neonatal records); family history; and home environment (passive smoking; sleep patterns, maternal-child stress indices). Behavior, cognitive skills, attention, and health-related quality of life were assessed with standardized instruments to assess co-morbidities (potential SDB outcomes). Analysis of the longitudinal data provided cognitive-developmental trajectories that were evaluated in relationship to SDB. The case-control arm confirmed and extended the findings of the in-home assessments with comprehensive laboratory polysomnography, cephalometry, and objective measures of sleepiness (Multiple Sleep Latency Tests) in three groups of children: definite SDB by home assessment; equivocal SDB; and no SDB. Collection of comprehensive polysomnographic data helped to identify which measures best discriminated symptomatic (e.g., snoring, sleepy) from asymptomatic children.