This article examines the rates of detection for major depression and other depressive disorders by family physicians as well as the differences between detected and undetected cases in terms of a variety of demographic and clinical variables. A total of 1,580 family practice patients completed a screening form and were rated by their physician. Patients with elevated Center for Epidemiologic Studies-Depression Scale (CES-D) scores were oversampled for possible interviews using the Structure Clinical Interview for DSM-III-R (SCID). In the resulting weighted sample, family physicians detected 34.9% of cases of major depression and 27.9% of cases of any depressive disorder. Detection was associated with pharmacological and psychological intervention. However, the undetected cases tended to be mildly depressed and higher functioning. Presence of a current anxiety disorder facilitated detection. Overall, the mildness of undetected depression and associated impairment have implications for estimates of the consequences of primary care physicians' low rates of nondetection and for the development of interventional strategies to improve their performance.