BACKGROUND: NCQA accreditation is a “Good Housekeeping Seal” for MCOs to evaluate how well a health plan manages its clinical and administrative systems in continuously improving health care for its members. A key standard in NCQA accreditation is demonstrating quality improvement. This case study outlines how manufacturer-funded outcomes research was used by an MCO for the NCQA quality improvement standard. OBJECTIVE: A national MCO and its behavioral health carve-out sought to understand current prescribing practices by its primary care physicians and psychiatrists for the patient population receiving antidepressant prescriptions. METHODS: Cross-sectional retrospective analyses were conducted using the prescription, diagnosis, and eligibility databases of the national MCO and its behavioral health subsidiary. The population included adults who received at least one antidepressant prescription in mid-1995. RESULTS: By prescriber type, 77% of patients who received an antidepressant prescription from a psychiatrist also had a depression diagnosis, compared to only 32% of patients who were prescribed an antidepressant by a primary care physician. Overall, only 34% of patients treated with antidepressant also received a recorded depression diagnosis. CONCLUSIONS: Based on these findings, the MCO and its behavioral health carve-out implemented interventions directed at primary care physicians and psychiatrists to improve the recognition and treatment of depression. A collaborative follow-up study is now under way to compare more recent data to the original baseline findings to demonstrate improvement in the quality of care provided to antidepressant patients.