This paper focuses on the emergence, institutionalization and transformation of the “magic formula”, which has set the rules of how the seven members of the Swiss Government (Federal Council) should be distributed among the four major parties (2 + 2 + 2 + 1) from 1959 to 2003. Using various kinds of sources, we look at the practices and logics of situation which are constitutive of this governmental coalition. The persistence of this type of coalition does not fit with coalition theories and is very often seen as an expression of the “Swiss consensus”.