This article analyzes the use of social and environmental clauses in public procurement contracts. After describing the current French legal context, it shows how a mechanism design approach can explain the factors that theoretically justify such practices, potentially including favoritism and rent-seeking. An empirical analysis is then carried out on the French public procurement data set for the year 2017. It illustrates the weight of political preferences in the choice to resort to social clauses and the weight of the preferences of the local chief executive to explain the use of environmental clauses. It also highlights that social and environmental clauses do not seem to be used as a tool for favoritism.