The essay examines some profiles of the roman concubinage, from the archaic period to the dominate. A particular focus is dedicated to the social esteem of the ‘concubinae’ in the middle and late Republic and to the shifts of the legal institute in the Principate. The author verifies some current assumptions about the possibility of concubinage with ‘mulieres ingenuae’ in the late Principate, with the help of the analysis of legal innovations in the late antiquity about acknowledgement of the illegittimate children. sons (and about the connected ‘de facto’ marriages).