Twenty states are undertaking efforts to encourage multiple payers to take part in medical home initiatives. The participation of many payers provides impetus for primary care practices to transform into medical homes, helps distribute the costs of creating medical homes, and leads to coordinated provider payment. One key concern, however, is the potential for uncompetitive behavior, something that antitrust laws seek to protect consumers against. In a Commonwealth Fund issue brief, experts from the National Academy for State Health Policy provide examples of how states with multipayer medical home programs are using legislative, executive, or regulatory policies to address antitrust concerns.