Going back to the genesis the “1% housing” law (which obliges French companies to invest in housing since 1953) invites a questioning of the place of private companies in the construction process of social politics in the 20^th Century. In fact, if the State wishes to resolve the problem of chronic deficit and the dilapidation of French housing since the founding law of 1894, it does not know how to give itself the means to practice such a policy, which would remain derisory in regard to assessed needs in the time between the two WorldWars. Confronted with this deficit in public investment, several investigations underline, to the contrary, the quantitative importance of managerial efforts in this matter. Of course, it appears to be impossible at first to directly associate industrials with the construction of low-cost housing. However, since the 1920s, the State has developed the volition to find a compromise with these very efficient private participants. The industrialists, who were at first reluctant to give up any of their freedom, became aware of the need for evolution in the ‘30s. This is how it was possible to reach the 1953 compromise, which imposed the principal of investment on companies, but gave them a great amount of freedom as to the modalities of this investment.