This randomized trial showed no effect of early adenotonsillectomy, as compared with watchful waiting, on the primary outcome of attention and executive functioning in children with obstructive sleep apnea. Many secondary outcomes favored early surgery. The childhood obstructive sleep apnea syndrome is associated with numerous adverse health outcomes, including cognitive and behavioral deficits. 1 The most commonly identified risk factor for the childhood obstructive sleep apnea syndrome is adenotonsillar hypertrophy. Thus, the primary treatment is adenotonsillectomy, which accounts for more than 500,000 procedures annually in the United States alone. 2 Nevertheless, there has been no controlled study evaluating the benefits and risks of adenotonsillectomy, as compared with watchful waiting, for the management of the obstructive sleep apnea syndrome. The Childhood Adenotonsillectomy Trial (CHAT) was designed to evaluate the efficacy of early adenotonsillectomy versus watchful waiting with supportive . . .