A study was conducted to examine reactions to success and failure in young and elderly subjects. Young and aged women, previously classified as internals or externals according to scores on a version of Rotter's (1966) Locus of Control Scale, were asked to work on cognitive problems while listening to bursts of noise. Two experimental conditions were created. One group (perceived success) was led to believe they were successfully avoiding bursts of noise by correctly solving the problems. A second group (perceived failure) believed they were unsuccessful at the problems and not avoiding noises. To test the generality of the effects of the treatments, subsequent performance was assessed on first, a similar task administered by the original experimenter, and secondly, on a dissimilar task given by a different experimenter in another setting. Results on a similar task indicated that subjects showed poor performance following failure regardless of age or locus of control classification. However, internals performed better than externals after both success and failure treatments. Testing the generality of these effects with a dissimilar task, results indicated that externals tended to perform somewhat more poorly after failure and internals somewhat better after failure. However, these I-E differences in reactions to success and failure were largely due to the elderly group, and old-externals showed the poorest performance after failure. The results were interpreted in terms of the particular importance of locus of control as a determinant of adaptability to stress in the elderly.