In the 'pre-history' of Argentina's labour movement lie the mutual-benefit
societies. Although these associations embraced almost half of the workers
of Buenos Aires at the time of the Centenario (1910) little is known about
them. The article explores the main parameters shaping the development of t
he mutual benefit societies, their relationship to the immigrant communitie
s and their role in relation to social security. It traces, finally, the am
biguous relationship between the mutual benefit societies and the emergence
of Peronist trade unionism in the mid-1940s.