OBJECTIVE: To evaluate overprescribing of antidepressant medication for minimal or mild depression. METHOD: Electronic records data from 4 large health care systems identified outpatients aged 18 years or older starting a new episode of antidepressant treatment in 2011 with an ICD-9 diagnosis of depressive disorder (296.2, 296.3, 311, or 300.4). Patient Health Questionnaire-9 (PHQ-9) depression severity scores at time of treatment initiation were used to examine the distribution of baseline severity and the association between baseline severity and patients' demographic and clinical characteristics. RESULTS: Of 19,751 adults beginning treatment in 2011, baseline PHQ-9 scores were available for 7,051. In those with a baseline score, 85% reported moderate or severe symptoms (PHQ-9 score of 10 or more), 12% reported mild symptoms (PHQ-9 score of 5 to 9), and 3% reported minimal symptoms (PHQ-9 score of less than 5). The proportion reporting minimal or mild symptoms when starting treatment increased with age, ranging from 11% in those under age 65 years to 26% in those aged 65 and older. The proportion with minimal or mild symptoms was also moderately higher among patients living in wealthier neighborhoods and those treated by psychiatrists. Nevertheless, across all subgroups defined by sex, race/ethnicity, prescriber specialty, and treatment history, the proportions with minimal or mild symptoms did not exceed 18%. Secondary analyses, including weighting and subgroup analyses, found no evidence that estimates of baseline severity were biased by missing PHQ-9 scores. CONCLUSIONS: In these health systems, prescribing of antidepressant medication for minimal or mild depression is much less common than suggested by previous reports. Given that this practice may sometimes be clinically appropriate, our findings indicate that overprescribing of antidepressants for mild depression is not a significant public health concern.