Objective: We evaluated the effectiveness of a continuing medical education program, Physician Asthma Care Education, in improving pediatricians' asthma therapeutic and communication skills and patients' health care utilization for asthma. Methods: We conducted a randomized trial in 10 regions in the United States. Primary care providers were recruited and randomly assigned by site to receive the program provided by local faculty. The program included 2 interactive seminar sessions (2.5 hours each) that reviewed national asthma guidelines, communication skills, and key educational messages. Format included short lectures, case discussions, and a video modeling communication techniques. We collected information on parent perceptions of physicians' communication, the child's asthma symptoms, and patients' asthma health care utilization. We used multivariate regression models to determine differences between control and intervention groups. Results: A total of 101 primary care providers and a random sample of 870 of their asthma patients participated. After 1 year, we completed follow-up telephone interviews with the parents of 731 of the 870 patients. Compared to control subjects, parents reported that physicians in the intervention group were more likely to inquire about patients' concerns about asthma, encourage patients to be physically active, and set goals for successful treatment. Patients of physicians that attended the program had a greater decrease in days limited by asthma symptoms (8.5 vs 15.6 days), as well as decreased emergency department asthma visits (0.30 vs 0.55 visits per year). Conclusions: The Physician Asthma Care Education program was used in a range of locations and was effective in improving parent-reported provider communication skills, the number of days affected by asthma symptoms, and asthma health care use. Patients with more frequent asthma symptoms and higher health care utilization at baseline were more likely to benefit from their physician's participation in the program.