CONTEXT: Insufficient evidence exists for recommendation of specific effective treatments for older primary care patients with minor depression or dysthymia. OBJECTIVE: To compare the effectiveness of pharmacotherapy and psychotherapy in primary care settings among older persons with minor depression or dysthymia. DESIGN: Randomized, placebo-controlled trial (November 1995-August 1998). SETTING: Four geographically and clinically diverse primary care practices. PARTICIPANTS: A total of 415 primary care patients (mean age, 71 years) with minor depression (n = 204) or dysthymia (n = 211) and a Hamilton Depression Rating Scale (HDRS) score of at least 10 were randomized; 311 (74.9%) completed all study visits. INTERVENTIONS: Patients were randomly assigned to receive paroxetine (n = 137) or placebo (n = 140), starting at 10 mg/d and titrated to a maximum of 40 mg/d, or problem-solving treatment-primary care (PST-PC; n = 138). For the paroxetine and placebo groups, the 6 visits over 11 weeks included general support and symptom and adverse effects monitoring; for the PST-PC group, visits were for psychotherapy. MAIN OUTCOME MEASURES: Depressive symptoms, by the 20-item Hopkins Symptom Checklist Depression Scale (HSCL-D-20) and the HDRS; and functional status, by the Medical Outcomes Study Short-Form 36 (SF-36) physical and mental components. RESULTS: Paroxetine patients showed greater (difference in mean [SE] 11-week change in HSCL-D-20 scores, 0.21 [0. 07]; P =.004) symptom resolution than placebo patients. Patients treated with PST-PC did not show more improvement than placebo (difference in mean [SE] change in HSCL-D-20 scores, 0.11 [0.13]; P =.13), but their symptoms improved more rapidly than those of placebo patients during the latter treatment weeks (P =.01). For dysthymia, paroxetine improved mental health functioning vs placebo among patients whose baseline functioning was high (difference in mean [SE] change in SF-36 mental component scores, 5.8 [2.02]; P =. 01) or intermediate (difference in mean [SE] change in SF-36 mental component scores, 4.4 [1.74]; P =.03). Mental health functioning in dysthymia patients was not significantly improved by PST-PC compared with placebo (P>/=.12 for low-, intermediate-, and high-functioning groups). For minor depression, both paroxetine and PST-PC improved mental health functioning in patients in the lowest tertile of baseline functioning (difference vs placebo in mean [SE] change in SF-36 mental component scores, 4.7 [2.03] for those taking paroxetine; 4.7 [1.96] for the PST-PC treatment; P =.02 vs placebo). CONCLUSIONS: Paroxetine showed moderate benefit for depressive symptoms and mental health function in elderly patients with dysthymia and more severely impaired elderly patients with minor depression. The benefits of PST-PC were smaller, had slower onset, and were more subject to site differences than those of paroxetine.