Asthma imposes a growing burden on society in terms of morbidity, quality of life, and healthcare costs. Although federally sponsored national surveys provide estimates of asthma prevalence, these surveys are not designed to characterize the burden of asthma by self-reported disease activity. We sought to characterize asthma burden in the United States. This study was based on a cross-sectional random-digit-dial household telephone survey designed to identify adult patients and parents of children with current asthma. Global asthma burden was comprised of three components: short-term symptom burden (4-week recall), long-term symptom burden (past year), and functional impact (activity limitation). Using this construct, only 10.7% of individuals were classified as having a global asthma burden consistent with mild intermittent disease, and 77.3% had moderate to severe persistent disease. These results suggest that a majority of the United States population with asthma experiences persistent rather than intermittent asthma burden. In addition, the discordance in type and distribution of asthma symptoms reported by individual subjects suggests that the exact estimate of the burden of asthma is related to how the National Asthma Education and Prevention Program classification is operationalized. Inquiry into recent day or nighttime symptoms alone underestimates the burden of asthma and may lead to inadequate treatment of asthma based on national guideline recommendations.