Asthma is a highly prevalent disease that affects the quality of life of many people in the United States. Yet there is limited descriptive epidemiological understanding of the disease, particularly at the state and local levels. Minimal surveillance of asthma is occurring across the country. Surveillance of a disease requires that public health workers have the ability to accurately identify cases, have access to needed data, and have adequate resources so that they can collect, assess, report, and use the data-all considerable challenges in the case of asthma. We consider four groups of questions that asthma surveillance should address: (1) How much asthma is there and what are the trends in asthma occurrence over time? (2) How severe is the asthma and what are the trends in asthma severity over time? (3) How well is asthma controlled and what are the trends in asthma management over time? (4) What is the cost of asthma? Because wise decision making in public health depends on the availability of appropriate data for program planning, implementation, and evaluation, we encourage increased surveillance of asthma in jurisdictions across the country.