Three studies predicted and found that the individual's conformism values are one determinant of whether behaviour is guided by other personal values or by social norms. In Study 1 (N =50), pro-gay law reform participants were told they were either in a minority or a majority in terms of their attitude towards the law reform. Only participants who were high in conformism values conformed to the group norm on public behaviour intentions. In studies 2 (N =42) and 3 (N =734), participants played multiple choice prisoner's dilemma games with monetary incentives. Only participants who considered conformism values to be relatively unimportant showed the expected connections between universalism values and altruistic behaviour. Study 3 also established that the moderating effect of conformism values on the relation between universalism values and altruistic behaviour was mediated through experienced sense of moral obligation.