The analyses of Pomp. D.17.2.62 allows to postulate that it was a jurisprudential opinion about the importance of communiter vendere as a condition to apply iudicium societatis. This is the premise of a complex reserch about the undefinite figure of communiter gerere, in the middle between societas and communio,as we can see in the ancient texts. The study retraces also the last century doctrinal debate, catching others important observations. After all it's possibile to conclude that communiter gerere is able to generate obligations and to apply actio pro socio. This has to be framed in the context of the constant development of the various forms of society, every time directed to different objects.