The abundance of private and voluntary associations was a key characteristic of the Roman world, in the West and in the East, during the late Republic and the High Empire.1 Most of the time, those communities were called collegia, corpora or sodalicia and their social recruitment was rooted in the urban plebs, the plebeians.2 From a certain point of view, they were very diverse. Indeed, their specific names suggested that their members decided to unite for different reasons: because they had the same occupation, the same geographical origin or the same devotion to a specific god, for instance. Nevertheless, they were usually engaged in very similar activities. All of them were religious associations.