Pediatric Asthma Controller Trial (PACT) is a study to determine the comparative effectiveness of inhaled corticosteroid, a leukotriene receptor antagonist, or a combination medication of inhaled corticosteroid and long-acting beta2-agonist in children with mild asthma. The study addresses a critical question facing primary care physicians about the optimal choice for initiating daily long-term treatment in children. The primary study outcome is the percentage of days without asthma during the 12-month treatment period. Recruitment began in August, 2002. A total of 300 children were assigned to one of three active treatment arms for 12 months: active ICS; a combination of active ICS and salmeterol; or active montelukast (LTRA). Major outcomes on the follow-up of 277 children were presented in May, 2005 at the American Thoracic Society meeting.