It has been suggested that people in racial/ethnic minority groups are healthier when they live in areas with a higher concentration of people from their own ethnic group, a so-called ethnic density effect. Ethnic density effects are still contested, and the pathways by which ethnic density operates are poorly understood. The aim of this study was to systematically review the literature examining the ethnic density effect on physical health, mortality, and health behaviors. Most studies report a null association between ethnic density and health. Protective ethnic density effects are more common than adverse associations, particularly for health behaviors and among Hispanic people. Limitations of the literature include inadequate adjustment for area deprivation and limited statistical power across ethnic density measures and study samples.