Much of emergency department use is avoidable, and high-quality primary care can reduce it, but performance measures related to ED use may be inadequately risk-adjusted. To explore associations between emergency department (ED) use and neighborhood poverty, we conducted a secondary analysis of Massachusetts managed care network data, 2009-2011. For enrollees with commercial insurance (n = 64,623), we predicted any, total, and total primary-care-sensitive (PCS) ED visits using claims/enrollment (age, sex, race, morbidity, prior ED use), network (payor, primary care provider [PCP] type and quality), and census-tract-level characteristics. Overall, 14.6% had any visit; mean visits per 100 persons were 18.8 (±0.2) total and 7.6 (±0.1) PCS. Neighborhood poverty predicted all three outcomes (all P< .001). Holding providers accountable for their patients' ED use should avoid penalizing PCPs who care for poor and otherwise vulnerable populations. Expected use targets should account for neighborhood-level variables such as income, as well as other risk factors.