This sociology thesis focuses on recent pension reforms in France between the 1970s and 1990s. The last reform favourable to pensioners dates from 1983, with the lowering of the retirement age from 65 to 60. In 1993, the first reform unfavourable to pensioners took place with the increase in the length of contribution, the length of the average annual salary and the indexation on prices. From a sociological perspective of controversies, public policies, statistics and justifications, this work proposes to look back at the pension reforms between the 1970s and the 1990s, based on a cross analysis of the archives of trade unions (CFDT and CGT), administrations (Social Security Department and Budget Department, Ministry of Social Affairs and Economy) and employers (UIMM and CNPF). Various struggles between actors concerning the problematisation of pensions and the organisation of the financial circuit of the Social Security system are thus studied. The thesis is in dialogue with the literature on the history of social security and the social state. It proposes to analyse social security and its policies from an approach that combines studies of problematizations, financial circuits and actors' strategies. The thesis defends a main result: employment policies framed the content of pension policies between the mid-1970s and 1993. During the 1970s, pensions and early retirement were progressively used to take older people out of the labour force. From 1983 onwards, the adoption of the policy of competitive disinflation led to a reduction in pension expenditure and the removal of the contribution rate from the legitimate parameters of the reforms. This thesis thus proposes a history of pension reforms that places greater emphasis on employment policies than the usual accounts, which focus on the ageing of the population. The reversal of pensions between reforms favourable and unfavourable to retirees is thus understood in the light of the shift in employment policies. Other results are also presented in this work. They concern the link between statistics and reforms, the problematisation of pensions, the use of indicators of pension profitability and the construction of financial circuits.