This guide equips advocates and other changemakers with critical information for advancing equity in the Health Insurance Marketplace, including program basics, an overview of major challenges to accessing coverage and health services, and a summary of policy opportunities for advancing equity. It covers the following topics:Marketplace overview key population characteristics providers and service delivery financing details barriers to access, quality, and equitable outcomes disparities primary oversight entities and accountability mechanisms policies and actions to reduce barriers and disparities a vignette illustrating the benefits of the Marketplace additional resources and a glossary This guide is part of a larger project on inequities and policy levers in the US health care system. For the complete guide, visit https://www.urban.org/projects/guide-equity-us-health-care-system.