AbstractThe paper explores the relationship between an individual's preference for cooperation and the establishment of cooperative norms. Our aim is to provide an experimental test of the hypothesis (Fehr and Gachter, 2002) according to which the individuals' willingness to punish defectors in social dilemma games favours the establishment of a common rule of behaviour leading to increased levels of cooperation. We conduct two experiments in which individuals decide both whether to participate in a common project and the institutional rules determining how the profits of the project were to be shared among the participants in the group. Our main question is to analyse whether high contributors react to free riding behaviour by adopting punitive sanctions. We also interview our subjects in order to elicit their opinions on civic values and free riding behaviour. Our results partly contradict the initial hypothesis; however, with reference to the institutional choices, we find that individual ethics may play an important role.