Background: Delirium in older emergency department (ED) patients is common, associated with many adverse outcomes, and costly to manage. Delirium detection in the ED is almost universally poor. Objectives: The authors aimed to develop a simple clinical risk screening tool that could be used by ED nurses as part of their initial assessment to identify patients at risk of delirium. Methods: A prospective cross-sectional study of patients 65 years and older attending a single ED. Results: Of 320 enrolled patients, 23 (7.2%) had delirium. Logistic regression analysis revealed 3 risk factors strongly associated with delirium risk: cognitive impairment, depression, and an abnormal heart rate/rhythm. Weighting these variables based on the strength of their association with delirium yielded a risk score from 0-4 inclusive. A cutoff of 2 or more in that score would have given a sensitivity of 87%, specificity of 70%, and NPV of 99%, while avoiding further diagnostic workup for delirium in approximately two-thirds of all patients, when used as an initial screen. Conclusions: A simple risk screening tool using factors evident on initial nurse assessment can be used to identify patients at risk of delirium. Further trials are needed to test whether the tool improves patient outcomes. © 2014 Academy of Psychosomatic Medicine.