My work is a socio-historical study of the institution of the gymnasium in Egypt, of its evolution and role in the assertion of certain aspects of ‘Greek identity’ in Ptolemaic and early Roman times. It is divided into four sections. (1) Attention is devoted to the study of the gymnasium itself, as institution, analysing its diffusion, foundation, internal organisation and the role played by associations which were hosted therein. The constitution and the characteristics of the governing body (with special attention to the role of the gymnasiarchs) and the financial matters relevant to the gymnasium allow one to draw conclusions on its legal status and social role: it is shown how the gymnasium of Egypt operated in a completely different way from the traditional one which is normally assumed for the Greek poleis, especially of mainland Greece and above all Athens. A possible model of influence is suggested. (2) Starting from the rules of admission into the gymnasium and from the treatment of the outsiders, the social status and social composition of the members of the gymnasium are object of enquiry, focusing on the links with the army and the public administration. It is argued that the gymnasial community should be considered as a complex reality, formed by different components belonging to various levels of the social strata. (3) Educational, religious and recreational activities carried out in the premises of the gymnasium or strictly connected to it are taken into account to give an idea of the ‘daily life’ of the institution and of the ‘behaviour’ of its people, which was likely to be the result of a feeling of ‘shared identity’. (4) The concluding section draws the attention to the issue of identity of the people of the gymnasium more clearly: relation with the ‘others’ and idea of Greekness the people of the gymnasium had about themselves (influenced by the rulers’ policies), access to gymnasia, onomastics, elite classes, mixed marriages, reception of Egyptian burial methods and cults, advantage of ‘going Greek’. It is argued that, although having in the gymnasium the key-element for the assertion of their identity and status of Hellenes, the ‘Greeks’ of Egypt displayed complex patterns of mixed identities and were thoroughly embedded in the social, cultural, religious, and administrative environment of Egypt.