BACKGROUND: As part ofrecertification, the American Board of Internal Medicine requires its diplomats to complete at least 1 practice improvement module (PIM). We assessed whether completing anasthma-specific PIM resulted in improved patient outcomes. METHODS: Practices were the unit of randomization in thisclusterrandomizedtrial. Physicians in the intervention group were asked to complete the PIM through its planning phase. The primary outcome was the dispensing of an inhaled corticosteroid (ICS) after a postintervention visit forasthma. Secondary outcomes included patient reported processes ofcare,asthma-related heathcareuse, andasthmaseverity. Analyses were adjusted for baseline rates at thecluster-level as well as for individual sociodemographic characteristics. RESULTS: Eight practices (19 internists) wererandomizedto the intervention group and 8 practices (21 internists) to the control group. For the primary outcome, ICS fill rates, patients seen by intervention group physicians were not more likely to fill an ICS prescription in the postintervention period than patients seen by control group physicians (adjusted odd ratio [AOR], 1.00; 95% confidence interval [CI], 0.64-1.56). Patients seen forasthmaby intervention group physicians were less likely to receive a written action plan than patients seen by control group physicians (AOR, 0.67; 95% CI, 0.48-0.93); however, they were more likely to discuss potentialasthmatriggers (AOR, 1.62; 95% CI, 1.08-2.42) and had lower self-reportedasthmaseverity measures (unadjusted P = .03). Per-protocol analysis supported the latter 2 associations. CONCLUSION: A PIM designed to improveasthmacaredid not improve filling of ICS prescriptions but may have lessenedasthmaseverity through an increased discussion ofasthmatriggers. Comment in The impact of the ABIM's practice improvement modules on patient outcomes.