In this paper we explore the relationship between the individual’s preference for cooperation and the establishment of cooperative norms. Our aim is to provide an experimental test of the evolutionary hypothesis (see Carpenter, 2004, Fehr and Gachter 2002; Gintis 2000; Boyd, Bowles, Gintis and Richerson 2003; Bowles and Gintis 2004), according to which individuals are prepared to punish defectors in experimental social dilemma games because they want to enforce a social (“altruistic”) norm which may conduce to increasing their future payoffs, as in the case of sanctions against free riding behaviour. According to this line of research , the high levels of cooperation we observe in our societies can, therefore, be strictly related to the establishment of social norms which are able to enforce and maintain cooperation in the long run. We study the results of two experiments in which the individuals decided both whether to participate in a common project and the institutional rule according to which the profits of the project had to be shared among each of the participants in the group. They could choose between 1) a regime where gains were shared equally, regardless of individuals’ contributions and without sanctions and rewards (System A); 2) a regime where individuals were paid according to their marginal contribution, but the profits of the investments were lower than in the other contexts (System B); finally 3) a regime in which gains were shared equally (as in System A), but individuals were allowed to punish (and\or reward) free riding (cooperative) behaviours as in Sefton, Shupp and Walker (2007). Before the experiments took place, our subjects were required to fill a questionnaire composed of four sections, where their attitude to cooperate and their opinions on civic values and free riding behaviours were thoroughly explored. We then monitored the behaviour of potential free riders and cooperators in the game and their institutional choices. Our results partly contradict the evolutionary hypothesis in as much as System A and B received the largest shares of votes in almost all rounds and they were voted by free riders and cooperators alike. Thus, most individuals do not like sanctions (incentives) against defectors and free riders (cooperators), and their institutional preferences do not seem to be related to their willingness to cooperate. The inspection of individual data, however, reveals some interesting points. In fact, we can assert that System C was mostly chosen by cooperative individuals in response to observed free riding behaviour. Furthermore, when a cooperative individual chose C, she would tend to punish free riders and reward cooperators. Our conclusion is that, as far as the institutional choices are concerned, beside the profit motivations underlined in the evolutionary hypothesis, the ethical and cultural unobserved individual preferences play an important role. There is a number of individuals (limited in our experiments, ranging between 15 and 30 per cent of the entire population) who see cooperation as the “right” thing to do, and therefore are prepared to implement institutional rules that may favour this collective outcome. Most people in our experiments did not share these same values.