Despite the rapid growth of pay-for-performance programs in the United States, evidence of their impact on quality of care is limited. This study of 44 pediatric practices sought to determine whether coupling pay for performance with other interventions would accelerate improvement in the care of 13 380 children with asthma in those practices. The program rewarded practices with up to a 7% increase in their fee schedule, practice-level performance thresholds, and building improvement capacity for participating in the collaborative, achieving network. During the 3-year study period, the percentage of the network population of children with asthma who received optimal care increased from 4% to 88% and the proportion of children receiving influenza vaccine nearly tripled. This study demonstrated that pay for performance, when coupled with robust approaches for quality improvement, can accelerate transformation among pediatric health care providers.