Narrow provider networks are increasingly common in the individual health insurance market. Regardless of what system emerges from efforts to repeal and replace the Affordable Care Act, insurers are expected to continue to rely on narrow provider networks. The new administration has proposed to loosen federal network adequacy standards and delegate more authority to states. This paper examines how four states with significant regulatory experience have assessed and monitored the adequacy of provider networks in the nongroup market to ensure consumers have timely access to care. Their experience provides lessons for other regulators and policymakers in a changing nongroup market.