Background: Inhaled corticosteroids, when properly used, can offer considerable protection against asthma-related morbidity. However, adherence to prescribed inhaled steroids among children is low and rates differ markedly by population. The lowest rates of adherence and highest rates of morbidity are among inner-city and low income populations. Purpose: To describe the design of a school-based clinical trial in a largely minority population that is examining the efficacy of a school-based intervention intended to increase adherence to daily inhaled corticosteroids. Methods: The supervised asthma therapy study is a two-group randomized longitudinal trial. Children were randomly assigned to either school-based supervised asthma therapy or parent supervised asthma therapy. Children were followed longitudinally for 15 months. The primary outcome of the study is the time-averaged difference between the two groups in the percentage of children experiencing at least one asthma exacerbation each month. Results: A web-based data collection system was designed to capture data at school. A total of 295 students, recruited from community and school sites, who attended one of 36 urban elementary schools enrolled in the study and 290 were randomized. The average age of the students was 10.0 years (sd = 2.1), 91% were African American, 8% were white, and 1% were of other racial groups. 57% of students were male. The study has been recently completed and results are being analyzed. Conclusions: Intervention studies requiring daily medication supervision and daily data collection can be successfully conducted within the elementary school environment. © 2007 Elsevier Inc. All rights reserved.