Objectives: The study aimed to determine the prevalence of chronic illness and chronic pain in emergency department (ED) patients across demographic backgrounds. Methods: This was a cross-sectional study at an urban, level I trauma center with 98 000 annual visits. This was a prospective sample of adult patients presenting to the ED during a randomized distribution of daily 8-hour periods between June 4 and August 26, 2007. Prevalence of chronic illness was compared to subject demographics using logistic regression, and prevalence of chronic pain was compared using ordinal logistic regression. Results: Six thousand nine hundred sixty-one patients presented during the data collection periods; 3882 were eligible, and 3132 (82%) were enrolled (51.7% male; age, 41.1 ± 15.8 years; range, 18-98 years). Chronic illness was reported in 36.3% of patients and chronic pain in 34.9% of patients. Chronic illness was associated with homelessness (odds ratio [OR], 1.75; 95% confidence interval [CI], 1.17-2.61), family income less than $25 000 (OR, 2.27; 95% CI, 1.60-3.22), and lack of access to primary care facilities (OR, 2.68; 95% CI, 2.25-3.21). Chronic pain was associated with homelessness (OR, 2.56; 95% CI, 1.79-3.64), family income less than $25 000 (OR, 2.54; 95% CI, 1.91-3.39), and lack of access to primary care facilities (OR, 1.47; 95% CI, 1.26-1.70). Conclusions: Patient housing situation, family income, and perceived access to primary care medical facilities were associated with higher self-reported rates of chronic illness and chronic pain.