Tiered networks, which provide patients with a choice of medical providers at different price points, are an increasingly common feature of health insurance plans. This Commonwealth Fund–supported study in the American Journal of Managed Care found that, when certain physicians were excluded from a preferred provider organization network, most patients did not continue to see them. The researchers conclude that using cost-sharing to steer patients toward preferred physicians—those who provide superior quality at lower cost—may be an effective tool for improving value in health care.