We compare a partners condition where the same small group of subjects plays a repeated public good game to a strangers condition where subjects play this game in changing group formations. Subjects in the partners condition contribute from the first period on significantly more to the public...

In a series of experiments, we compare a situation where the same group of four subjects plays 25 repetitions of a public good game (partners condition) to a situation where subjects play this game in changing group formations over 25 periods (strangers condition). We observe that, on aggregate...