This study used experience sampling methodology to examine the relationship between stressful daily events and mood. Eighty-five male white-collar workers completed self-reports 10 times a day for 5 days. Controlling for individual differences in mood levels, multilevel regression analyses showed that events were followed by increases in negative affect (NA) and agitation (Ag) and by decreases in positive affect (PA). More unpleasant events were associated with greater changes in all three mood dimensions; controllability mitigated the effects of events on NA and PA. Prior events had persistent effects on current mood. High perceived stress (PS) was associated with greater reactivity of NA and PA to current events, whereas trait anxiety moderated reactivity of Ag. Results indicate that PS is related not only to a higher frequency of reported events but also to more intense and prolonged mood responses to daily stress.