This study examined the effect of mood states on mind wandering. Positive, neutral, and negative moods were induced in participants prior to them completing a sustained attention task. Mind wandering was measured by using the frequencies of both behavioral lapses and retrospective indices of subjective experience. Relative to a positive mood, induction of a negative mood led participants to make more lapses, report a greater frequency of task irrelevant thoughts, and become less inclined to reengage attentional resources following a lapse. Positive mood, by contrast, was associated with a better ability to adjust performance after a lapse. These results provide further support for the notion that a negative mood reduces the amount of attentional commitment to the task in hand and may do so by enhancing the focus on task irrelevant personal concerns.