The undocumented population is the largest group explicitly excluded from the Patient Protection and Affordable Care Act (ACA). This report provides a comprehensive review of the literature on the health and health care of undocumented immigrants in the U.S. and new data from the 2009 California Health Interview Survey (CHIS) and the Gruber MicroSimulation Model.

Findings: Existing research consistently finds undocumented immigrants with low rates of health insurance and health services use, and a heavy reliance on safety net providers. California data reinforce national trends on low coverage, access, and use, with findings of mixed advantages and disadvantages in health status. MicroSimulation models show undocumented immigrants will continue to have low health insurance coverage under the ACA; 5.1 million undocumented immigrants will be uninsured by 2016. Given the exclusion of most undocumented residents from health insurance, authors review policy options for improving coverage, access to care and health-related services for this population.