This study examined the hypotheses that positive mood enhances conformity and that negative mood reduces it. Participants were induced to feel positive, neutral, or negative moods and then answered, in private, six mathematical questions. They observed that wrong answers were unanimously given by five bogus participants for three of the questions. Conformity was measured by whether they indicated the erroneous answers given by these bogus participants in these three questions. The results were supportive of the hypothesis. The current results are consistent with past findings about mood differences in heuristic versus elaborative processing. Copyright © 2007 John Wiley & Sons, Ltd.