While most lifespan developmental theories of personality predict age-related changes in coping, little direct evidence exists for determining whether age differences in coping style are due to intrinsic developmental processes or to age differences in the kinds of stresses encountered. To evaluate age differences in coping strategies and whether these differences are attributable to intrinsic, age-based developmental processes or to differences in the objective or subjective nature of the illness stresses, 170 chronically ill adults completed six scales assessing coping strategies and objective and subjective measure of illness stress. The subjects (67 males, 103 females) who suffered from hypertension, diabetes mellitus, rheumatoid arthritis, and systemic blood cancers, ranged in age from 41 to 89 years. The coping strategies studied were information seeking, cognitive restructuring, emotional expression, wish-fulfilling fantasy, threat minimization, and self-blame. A follow-up interview with 151 subjects was completed 7 months later. An analysis of the results showed that age differences in adults' styles of coping appeared in the areas of threat minimization and information seeking. People over age 75 were more likely to cope by cognitively minimizing the threat posed by the illness and less likely to cope by seeking out information about their illness and its treatment. Results are consistent with theories suggesting that late life represents a shift from active to passive mastery, and that older people are more likely to cope with stress through self-reliance than by reaching out to friends or professionals. (BL)