U.S. emergency department (ED) visits by adults aged 65 and older increased from 15.9 million in 2001 to 19.8 million in 2009.1 Although the ED is an essential site of care for individuals with acute illness and injury, ED visits are more costly than primary care visits, and ED visits by older adults with complex medical histories and preferences of care may be less efficient than visits to primary care providers (PCPs), who typically already know the individual. Thus, number of ED visits has been identified as a possible measure of PCP performance,2 and reducing the number of these visits has been identified as a desirable outcome in randomized trials. These trials have demonstrated that greater access to primary care for chronically ill older adults can reduce ED visits, hospitalizations, and the cost of care.3–5 Despite the success of these interventions in selected populations, the relationship between availability of primary care and ED use in a general population of older adults has not been described