A long tradition in the help giving literature assumes that mood states determine the level of prosocial behaviour shown by individuals. Most research in this area has been conducted in the context of low cost prosocial behaviour, whereas research has been neglected in which participants were confronted with situations involving potential severe and dangerous negative consequences (i.e., high cost situations) with the help-giver risking his moral integrity and social disapproval (i.e., moral courage). To address this gap in the literature, the present studies investigate differential effects of positive and negative compared with neutral mood states on help giving versus moral courage. Study 1 shows that in situations requiring low cost helping, participants were more likely to help in positive and negative moods than those in a neutral mood, whereas in situations requiring moral courage (high cost), participants were comparably likely to help in each of the three mood conditions. In Study 2, we find that salience of moral norms mediates the interaction between type of prosocial behaviour and mood. Finally, Study 3 investigates whether the apparent discrepancy between help giving and moral courage as established by the differential impact of mood states can be determined still differently. It reveals that justice sensibility, civil disobedience, resistance to group pressure, moral mandates, and anger lead to moral courage, but not to help giving. Differences between these two types of prosocial behaviour are discussed. Copyright © 2009 John Wiley & Sons, Ltd.