We charted daily variations in intrusive thoughts to gain access to adult age differences in affective reactivity to daily stressors. On 100 days, 101 younger and 103 older adults reported stressors, intrusive thoughts, and negative affect. Although increments in intrusive thoughts were similar in both age groups on days with stressors, older adults' negative affect increased less than younger adults' on such days. In addition, (a) levels of intrusive thoughts and negative affect across study time were positively associated; (b) days with increased thoughts were days with increased negative affect; and (c) experiencing above-average intrusive thoughts about stressors strengthened affective reactions to stress. Relative to younger adults, all three associations were reduced in older adults. We tentatively conclude that normal aging dampens the stress-induced link between intrusive thoughts and affect. This dampening may contribute to preserved affective well-being and reduced affective reactivity to daily stress in old age.