Asthma is the most common chronic disease of children. In 1997 the National Asthma Education Program consensus panel, organized by the National Heart, Lung and Blood Institute (NHLBI), revised the guidelines for the care and management of children and adults with asthma1,2. The impact of these guidelines on asthma case in the U.S. is unclear since hospitalization rates and mortality continue to rise. We hypothesize that the use of clinical practice guidelines will enhance the quality of asthma care and be a more cost-effective approach to the management of childhood asthma. We propose to evaluate the efficacy of a program designed to adhere to the NHLBI guidelines on asthma management in an emergency department (E.D.)/observation unit (O.U.) setting. The study will utilize a prospective cohort design of all children 1-18 years seen in Connecticut Children's Medical Center (CCMC) E.D. for an asthma exacerbation. The specific study aims are: 1. To determine the ability of a busy, pediatric E.D. to comply with NHLBI guidelines for the management of acute childhood asthma and determine factors associated with non-compliance; 2. To determine the effect of complying with NHLBI guidelines on: a) the rate of asthma relapse, b) the efficiency of treatment as estimated by the time spent in the E.D. prior to disposition, c) the functional status of children during an acute asthma exacerbation using the Child Health questionnaire (CHQ); and 3. To evaluate the role of an O.U. in the management of acute childhood asthma: a) to evaluate the accuracy of the Asthma Clinical Pathway in determining patient disposition; b) to compare the functional status of children admitted to the two treatment sites (O.U. and inpatient unit) using the CHQ adjusted for illness severity; and, c) to estimate the cost-effectiveness of the O.U. (the incremental cost savings of hospital days avoided by using an alternative treatment site (O.U.) for childhood asthma) compared to the current standard inpatient setting. The ability to assess whether using standardized clinical guidelines is effective in improving the outcomes of an asthma exacerbation is critical to addressing the value of such guidelines for the management of childhood asthma. This study will provide a greater understanding of the health status of children with asthma and will address whether or not the alternative O.U. treatments provide similar physical and psycho-social outcomes to the traditional inpatient hospitalization. Additionally, an understanding of the economic impact that O.U.s can play in the care of children with asthma will assist policy-makers on appropriate allocation of limited resources.