We conducted an observational study to identify predictors of hand hygiene (HH) in the emergency department. Compliance with HH was 89.7% over 5,865 opportunities. Observation unit, hallway or high-visibility location, glove use, and worker type predicted worse HH. Hallway location was the strongest predictor (relative risk, 88.9% [95% confidence interval, 85.9%-92.1%]).