Clinical data about the efficacy and safety of controller medications for pediatric patients of all ages are limited, especially when compared with the amount of data available for medications for adults. The considerable data collected so far in adults about these therapeutic agents need to be confirmed in children because pharmacologic profiles will not necessarily be the same for children. Clinical research studies need to include younger populations so that the necessary information can be available for physicians who want to use controller therapy for their pediatric patients. Special challenges confront the pharmaceutical companies and the research investigators who undertake these clinical studies, but such challenges are surmountable.