His article deals with general features of moral behaviour from an economic perspective. Moral rules act as an enforcement mechanism replacing external sanctions with internal emotional sanctions such as guilt and shame. It is shown in many experiments and real life situations that morals influence the decision-making process and the outcomes. Moral attitudes help to overcome social dilemma situations if the actors’ intrinsic motivation is relatively high and if these moral attitudes are wide-spread. It is argued that to reject the (...) moral dimension means to restrict the relevance of economic theory. This paper emphasizes the importance of moral behaviour and offers a simple model of the effects of morality. (shrink)