['To test the hypothesis that children enrolled in Medicaid managed care health plans that provide asthma-specific communication to providers would be more likely to have adequate asthma medication filling.', 'We conducted a historical cohort study of 4498 children (2-17 years old) with moderate-severe asthma in Washington State and Tennessee Medicaid managed care programs from 2000 to 2002. Interviews with health plans were conducted to identify communication strategies health plans used to improve asthma care by providers in the plan. The main outcome measure was guideline-recommended filling of asthma preventer medications.', 'Children in plans that provided specific feedback to providers about asthma quality and notified providers when children had an asthma-related event had the highest mean days plus or minus SE of filling in the 365-day follow-up period (164.6 +/- 13 days) compared with children in plans with neither (135.3 +/- 10.8 days; P < .05). In children with the greatest asthma severity, enrollment in a plan with both features was associated with 27.1 additional days of filling (95% CI, 0.7-53.4 days) during the follow-up period.'] Is health plan notification and feedback to providers associated with increased filling of preventer medications for children with asthma enrolled in Medicaid?