The prevalence of asthma, a common chronic inflammatory disease of the airways, has risen sharply over the past 25-30 years, with the biggest increase found in children. Currently, more than 22 million Americans have asthma. Asthma also is associated with significant morbidity and mortality worldwide. Each year, asthma is responsible for $16 billion in direct and indirect costs due to health care utilization and loss of productivity, with over 14 million missed workdays. Asthma also accounts for almost 1.8 million emergency room visits and almost 500,000 hospitalizations annually. Therefore, assessment and monitoring of disease activity is critical to improve clinical and economic outcomes for patients with asthma. To help in this endeavor, practitioners and payers rely on evidence-based guidelines to classify disease severity, to guide treatment decisions, and to assess the degree of asthma control. In August 2007, the National Asthma Education and Prevention Program (NAEPP) updated its guidelines based on greater knowledge of disease pathophysiology and the development of newer therapeutic agents. This includes an increased emphasis on the need to establish disease severity, including the components of impairment and risk, as well as on the level of asthma control. Despite the availability of the NAEPP and other guidelines, asthma control often remains suboptimal. While numerous clinical and patient-reported measures are available, it is clear that the optimal monitoring schema for patients with asthma remains undefined. To clearly establish whether asthma control is attained, multiple measures are required and should include clinical and patient-reported assessments.