Objectives: To determine the sensitivity and specificity of a brief two-question depression screen for the detection of depression in older emergency department (ED) patients, and to determine the prevalence of depression in this population. Methods: This was a prospective, observational study. Participants included a convenience sampling of ED patients 70 years and older presenting to an urban teaching hospital over a 17-month period. Exclusions were refusal to participate, inability to communicate, and critical illness. Subjects were screened for depression with the previously validated Short Form Geriatric Depression Scale (SFGDS). Standardized scores on the SFGDS were used to determine the prevalence of depression. Patients were then given a previously published two-question depression screen, and results were compared with the SFGDS as the criterion standard. Sensitivity, specificity, and prevalence data are reported as proportions with 95% confidence intervals (95% CIs). Results: Two hundred sixty-seven of 327 eligible patients were enrolled. Forty-four (17%; 95% CI = 12% to 21%) scored positive for depression on the SFGDS. The sensitivity of the brief two-question depression screen was 84% (37/44; 95% CI = 70% to 93%), with a specificity of 61% (136/223; 95% CI = 55% to 67%) using a cutoff score of at least one of two positive responses. Conclusions: Depression is fairly prevalent in older ED patients. The brief two-question depression screen, using a cutoff score of at least one positive response, is promising for ED use. However, given lower specificity, patients scoring positive for depression should be followed up with a more specific tool such as the self-administered SFGDS prior to referral for further evaluation and treatment.