The present research tested the hypothesis that activity inhibition (as measured by the picture story exercise) moderates the relationship between stress and mood. Based on prior research that shows that (a) individuals high in activity inhibition restrain emotional and motivational impulses and (b) inhibiting negative emotion may lead to further emotional impairments, we assumed that individuals high in activity inhibition show evidence of increased negative mood when they are confronted with stressful events. Study 1 found evidence of increased negative mood-relevant thought among individuals high in activity inhibition who were confronted with the threat of social rejection. Study 2 found high negative mood among individuals high in activity inhibition who experienced many daily hassles. Also, participants high in activity inhibition reported a disproportionally higher amount of daily hassles in the middle (but not at the beginning) of a university semester. We suggest that this pattern of results can be accounted for by Wegner's (1994) theory of ironic effects of the suppression of thought and emotion.