Objective: The aim of the study was to assess the prevalence of limited health literacy in an urban emergency department (ED) and its association with sociodemographic variables. Methods: This was a cross-sectional study of patients presenting to the ED of an urban county hospital. For 3 months, we screened a convenience sample of patients presenting to the ED. Participants completed a brief demographic survey and a validated assessment of health literacy, the Short Test of Functional Health Literacy in Adults (S-TOFHLA). Multinomial logistic regression model was used to analyze data. Results: Of the 15′930 patients presenting to the ED, 5601 met inclusion criteria. Of eligible patients, 65% (3639) agreed to complete demographic surveys and 26% (960) of them agreed to complete the S-TOFHLA. The most common exclusions were inability to contact the patient and age less than 18 years. Participating patients were younger than those who declined (mean age, 36.8 compared to 40.8 [t = 7.49; P <.001]). Sex and ethnicity were not significantly different across groups. Of all participants, 15.5% possessed limited health literacy. Inadequate health literacy was independently associated with increasing age (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.05-1.10), non-English primary language (OR, 6.97; 95% CI, 2.76-17.6), male sex (OR, 1.82; 95% CI, 1.03-3.21), nonwhite ethnicity (OR, 2.66; 95% CI, 1.40-5.04), and years of education in the United States (OR, 0.63; 95% CI, 0.42-0.92). Marginal health literacy was associated with increasing age (OR, 1.03; 95% CI, 1.00-1.05); male sex (OR, 1.84; 95% CI, 1.04-3.24); ethnicity (OR, 2.08; 95% CI, 1.12-3.85); and a housing status of homelessness (OR, 9.66; 95% CI, 2.33-40.0), living with friends (OR, 4.59; 95% CI, 1.18-17.9), or renting (OR, 4.16; 95% CI, 1.21-14.3). Moderate to high correlation among housing variables was observed. Conclusions: Of patients enrolled in the study, 15.5% have limited health literacy. Age, male sex, non-English first language, nonwhite ethnicity, limited education, and unstable housing were associated with limited health literacy.