Despite increased scientific knowledge about asthma and improved therapeutic options, the disease continues to cause significant morbidity and mortality. The National Asthma Education and Prevention Program Expert Panel has updated its clinical guidelines on asthma medications, prevention of disease progression, and patient self-management. Diagnostic criteria have not changed, and identification of the disease relies on the physician's analysis of the patient's symptoms, family history, and spirometric measurements of lung function. Classification of asthma severity also has not changed, but many obstacles remain, including the variability of asthma and the classification system's inability to account for physical activity levels, which may result in significant underestimation of the severity of asthma. The National Asthma Education and Prevention Program recommends the use of written action plans with or without monitoring of peak expiratory flow, although evidence supporting these management techniques is inconclusive. Patients with asthma may benefit from earlier use of inhaled corticosteroids, which have been proven safe in the usual dosages. However, further studies are needed to determine whether inhaled corticosteroids can prevent the progression of asthma.