Does lack of documentation keep Mexican immigrants from seeing the doctor? Possibly. In this article, the authors analyze data from the 2007 California Health Interview Survey (2,600 documented and 1,038 undocumented immigrants) to identify differences in health care access and utilization among Mexican immigrants by documentation status. They found that undocumented immigrants from Mexico are 27 percent less likely to have had a doctor visit in the previous year and 35 percent less likely to have a usual source of care compared to documented Mexican immigrants, after controlling for confounding variables. The recently approved Patient Protection and Affordable Care Act will not reduce these disparities unless undocumented immigrants are granted some form of legal status.