Asthma is a common inflammatory condition affecting more than 7 million children in the United States alone, and tens of millions more globally. Despite effective preventive medications, medication nonadherence in children and adolescents is alarmingly high. Nonadherence can result in poor asthma control, which leads to decreased quality of life, lost productivity, increased health care utilization, and even the risk of death. Nonadherence in children and adolescents deserves special attention because they face unique barriers to adherence that change with age. Young children depend on adults for the delivery of asthma care, and their care is strongly influenced by parental motivation and attitudes and the home environment. As these children enter adolescence, they typically assume responsibility for their asthma care at the same time that they are claiming their independence and possibly experimenting with high-risk behaviors. Morbidity and mortality, as well as nonadherence, appear to be greatest among adolescents and minority children. Although no perfect tool for measuring adherence exists, objective methods, such as electronic monitoring, can provide valuable information to health care providers. Beyond asthma self-management and education, no specific resource-heavy adherence interventions have proven consistently helpful. However, large-scale, well-designed studies on this subject are lacking. In light of the fact that nonadherence is a potentially modifiable factor that impacts on morbidity and mortality, it is worth pursuing further research to determine better interventions. It is likely, however, that no one answer exists, and interventions will need to be tailored to specific at-risk populations.