Rationalising budgetary choices, “Renewal of the public service system”, LOLF, RGPP and nowadays, MAP: from the 60s up until today, the evaluation of public policies has addressed a never ending need that is constantly being reinvented: improved governance of public action. Despite this, the concept of evaluation faced a challenging situation in France: one that was characterised by the fragile institutionalisation of this concept, both ever changing and scattered. In order to explain this random trajectory, four main matters are discussed from a socio historical perspective: evaluation as a method for legitimisation and countervailing, as a factor in the improved application of public programmes, as a tool for promoting sectoral policies and as a means for optimising public expenditure.