Background Since 2001, Massachusetts state law dictates that emergency department (ED) patients with limited English proficiency have the right to a professional interpreter. Methods one year later, for two 24-h periods, we interviewed adult patients presenting to four Boston EDs. We assessed language barriers and compared this need with the observed use and type of interpreter during the ED visit. Results We interviewed 530 patients (70% of eligible) and estimated that an interpreter was needed for 60 (11%; 95% confidence interval, 7–12%) patients. The primary interpreter for these clinical encounters was a physician (30%), friend or family member age ≥18 years (22%), hospital interpreter services (15%), younger family member (11%), or other hospital staff (17%). Conclusions We found that 11% of ED patients had significant language barriers, but use of professional medical interpreters remained low. One year after passage of legislation mandating access, use of professional medical interpreters remained inadequate.