Asthma is a very prevalent disease in the United States, and the incidence is rising for a variety of reasons. Although progress has been made on several therapeutic fronts, adherence to asthma therapy, particularly controller medications, remains poor. This review of data from the past five years will focus on factors associated with nonadherence, barriers to adherence, factors associated with adherence, and finally strategies for improving. Communication between the health care provider and patient is paramount in improving adherence to medical therapy for asthma and thereby improving control of the disease.