Background: Community studies have documented prevalence rates of psychological disorders among older individuals. Further, a growing number of studies have examined depression in older medical patients. However, little is known about the prevalence of a broad range of psychological disorders and psychosocial stressors among older primary care patients. The purpose of the present study was to characterize psychological disorders and psychosocial stressors in older primary care patients and identify differences with younger patients. Methods: Descriptive survey; criterion standard. Five hundred thirty-four patients 65 years and older and 2466 patients less than 65 years old recruited from eight primary care sites. The Patient Health Questionnaire (PHQ) was employed to assess major depressive disorder, other depressive disorder, panic disorder, other anxiety disorder, probable alcohol abuse/dependence, somatoform disorder, bulimia nervosa, and binge eating disorder. Common psychosocial stressors were also assessed. Patient-reported health status was measured by the Medical Outcomes Study Short Form 20 (SF-20). Results: Older patients were much less likely than younger patients to have a psychological disorder (5% vs. 17%). Also, older patients had significantly less severe psychological symptom (4.7 vs. 8.0) and psychosocial stressor (2.3 vs. 4.7) scores. Worrying about health (10%), weight (9%), and a recent bad event (8%) were the most common stressors among the older group. Like younger patients, older patients who suffered from psychological symptoms and disorders experienced substantial functional impairment. Conclusions: Prevalence rates of psychological disorders and psychosocial stressors differ greatly between younger and older primary care patients and, somewhat contrary to clinical intuition, are lower among older patients.