This policy brief from Families USA describes the issue of network adequacy and its importance for achieving health equity for communities of color, individuals who speak languages other than English, and other populations experiencing health disparities. As more previously uninsured individuals and families gain access to commercial health insurance under the Affordable Care Act, it is vital that the health care providers in the networks offered by these health insurance plans are adequate to meet the needs of all the insured population. The policy brief describes some best practices in defining network adequacy, including definitions of essential community providers, in state-based health insurance marketplaces being implemented under the Affordable Care Act.