OBJECTIVE: The authors’ goal was to determine whether improved outcomes from enhanced acute-phase (3-month) treatment for depression in primary care persisted. METHOD: They conducted a 19-month follow-up assessment of 156 patients with major depression in the Collaborative Care intervention trials, which had found greater improvements in treatment adherence and depressive symptoms at 4 and 7 months for patients given enhanced acute-phase treatment than for patients given routine treatment in a primary care setting. Sixty-three of the 116 patients who completed the follow-up assessment had received enhanced treatment, and 53 had received routine treatment in primary care. The Inventory for Depressive Symptomatology and the Hopkins Symptom Checklist were used to measure depressive symptoms. Automated pharmacy data and self-reports were used to assess adherence to and adequacy of pharmacotherapy. RESULTS: At 19 months, the patients who had received enhanced acute-phase treatment did not differ from those who had received routine primary care treatment in clinical outcomes or quality of pharmacotherapy. CONCLUSIONS: Even though enhanced acute-phase treatment of depression in primary care resulted in better treatment adherence and better clinical outcomes at 4 and 7 months, these improvements failed to persist over the following year. Continued enhancement of depression treatment may be needed to ensure better long-term results.