This study evaluated defense mechanism differences between younger and older adults and also assessed the relationship between defense mechanisms and perceived stress, in order to provide evidence of construct validity of a self-reported defense mechanisms scale. Community-dwelling younger (n = 259; M age = 19.7 years) and older adults (n = 69; M age = 70.8 years) completed the Defense Style Questionnaire and the Perceived Stress Scale. Whereas there were no age differences on adaptive defense mechanisms, younger adults scored higher than older adults on the Acting Out, Passive-Aggression, and Regression maladaptive defense mechanism scales. Maladaptive defenses were significantly and positively correlated (r = .57) with perceived stress. Cross-sectional results suggest a general stability of adaptive defense mechanisms across the lifespan but a lessening of maladaptive defense mechanisms with advancing age. These results dispel the myth that old age is associated with inevitable psychological impairment and suggest some specific positive psychological adaptations with age. The correlational findings provide partial support for the construct validity of a self-report measure of defense mechanisms.