This study evaluated the Penn State Worry Questionnaire, Penn State Worry Questionnaire-Abbreviated, and the Generalized Anxiety Disorder Questionnaire-IV for identifying generalized anxiety disorder in older medical patients. Participants were 191 of 281 patients screened for a clinical trial evaluating cognitive-behavior treatment, n = 110 with generalized anxiety disorder, 81 without. Participants completed the Penn State Worry Questionnaire and Generalized Anxiety Disorder Questionnaire-IV at pretreatment. Kappa coefficients estimated agreement with the Structured Clinical Interview for Diagnosis. Receiver operating characteristic curves compared sensitivity and specificity of self-report measures. The Penn State Worry Questionnaire (cutoff = 50) provided the strongest prediction of generalized anxiety disorder (sensitivity, 76%; specificity, 73%; 75% correctly classified; kappa = .49. Item 2 of the Generalized Anxiety Disorder Questionnaire-IV demonstrated comparable accuracy. The Penn State Worry Questionnaire, Generalized Anxiety Disorder Questionnaire-IV, and briefer versions of these measures may be useful in identifying late-life generalized anxiety disorder in medical settings.