Objective: The study examined whether education level was associated with benefits derived from a self-management intervention. Because such interventions increase one's sense of control, it was hypothesized that persons with less education, who generally have a diminished sense of control, would derive greater benefit. Methods: A randomized trial was conducted with 361 patients aged 60 and older with type 2 diabetes or chronic obstructive pulmonary disease and mild to moderate depression. The intervention provided individualized contacts (two to ten) with nurses who taught participants to take control of their disease. Results: Positive effects on depression, health-related quality of life, feelings of mastery, and self-efficacy were confined to patients with more education; those with only a primary education did not benefit. Conclusions: Only more highly educated patients profited from a cognitive-behavioral approach to self-management. Patients with chronic conditions who have less education may derive greater benefits if environmental adversities or lower cognitive abilities are taken into account.