We conducted a review of 164 relevant publications to consolidate the evidence on gaps in the quality of asthma care, the impact of those gaps, and the costs and benefits of closing those gaps. Researchers used a wide variety of definitions for measures of quality asthma care, clinical and utilization end points, and disease severity. Gaps in care were most evident for pharmacologic treatment, particularly the underuse of inhaled corticosteroids, with median usage rates of 40%; however, in studies with large proportions of black subjects, the inhaled corticosteroid usage rate was only 32%, compared with 51% for nonminority populations. Studies on outcomes focused on emergency department visits, hospital admissions, and missed school days. Because only 6 studies included information on the costs of improving asthma care, no consensus estimates of the cost/benefit ratio for better asthma care could be derived. There was insufficient evidence in the literature for assessment of the impact of gaps in care and the costs of closing those gaps. More economic evaluations of the impact of gaps in asthma care and of interventions to improve asthma control are needed. Future research on gaps in asthma care and their impact must use standardized definitions for key variables such as disease severity and care utilization to allow comparisons across studies and building of an evidence base that is convincing for policy makers and purchasers of care. Pediatrics 2009; 123:S199-S204 I N 2002, Ͼ30 million US individuals reported having been diagnosed as having asthma, including 122 per 1000 children (which made asthma the most common chronic disease among children) and 106 per 1000 adults. The prevalence of the disease remains at historically high levels. 1 In 2004, the total estimated annual costs of treating asthma were approximately $16.1 billion, of which $11.5 billion were direct costs. 2 Prescription drugs accounted for the largest single component of these direct costs ($5 billion), and hospital care represented one third of the $11.5 billion. 2 Although recent advances in pharmacotherapy have made asthma a highly treatable disease, research suggests that treatment often falls short of recommended care; according to a 2001 study, 3 74% of children with moderate/ severe asthma in a national sample did not receive adequate treatment. Despite their higher prevalence of disease, minority children are less likely than nonminority children to receive adequate treatment. 4 Two Rand studies showed that only 43% of adult patients and only 44% of children who used a rescue inhaler Ն3 times per day were given maintenance treatment. 5,6 Recognition by policy makers, providers, and the public of the discrepancies between recommended care and care that is actually received has led to initiatives to improve the quality of asthma care, such as the Healthy People 2010 initiative. 7 Although the quality of asthma care, treatment options, and the effects of the disease have been addressed extensively by the research community, ther...