This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Asthmatic children and adolescents living in low-income, inner-city communities are a high-risk population characterized by increased asthma-related morbidity and mortality. There is an important need to find strategies for improving long term asthma control in this population. Exhaled nitric oxide (eNO), a marker of bronchial inflammation, appears to be increased during periods of uncontrolled asthma and decreased during treatment with medicines for asthma. Companies have recently started to market equipment to measure eNO as a means of monitoring and enhancing asthma control, but no randomized clinical trial has yet addressed the question of whether such monitoring improves asthma outcomes. The purpose of this study is to determine whether selection of asthma therapy on the basis of eNO measurements combined with clinical parameters improves asthma control compared with therapy chosen solely on the basis of clinical parameters.