Notes that most individuals experience a decline in health status during old age. Paradoxically, there are proposals that older adults nevertheless maintain a positive sense of well-being, an indicator of successful aging. Data from the Berlin Aging Study (BASE), a locally representative sample of 516 men and women (aged 70-100+ yrs), suggest that cumulative health-related chronic life strains set a constraint on the potential of oldest old individuals to experience the positive side of life. The young old in BASE reported significantly higher positive subjective well-being than did the oldest old. Chronic illness and functional impairments limit well-being especially in very old age. (PsycINFO Database Record (c) 2012 APA, all rights reserved)