Three studies examined humor and adjustment to stressful events. In Study 1, patients with fibromyalgia syndrome (N = 22) reported on mental and physical adjustment, social interaction, and reappraisal of their illness. Dispositional humor was associated with reduced distress and fewer physical symptoms. Study 2 (N = 109) examined undergraduates’ reports of stressful events. Dispositional, self-enhancing, affiliative, and self-defeating humor showed direct effects on distress, which were mediated by social interaction and reappraisal. Moreover, dispositional and aggressive humor showed stress-buffering effects. Study 3 (N = 105) examined undergraduates’ adjustment to the September 11, 2001, attacks at 1 and 3 months postattack. At T1, affiliative humor showed a stress-buffering effect on distress. Social interaction mediated the relation of self-enhancing humor with reduced T1 distress, and mediated relations of aggressive and self-defeating humor with greater distress. Relations of T1 dispositional and self-defeating humor to changes in T2 distress were mediated by reappraisal.