Separatism in Belgium does not impose itself, on the conditions that the Belgian Economic and Monetary Union does not force on Flanders toa large a cost, that Wallonia accepts the political prerequisites for thefunctioning of that Union and that federalism really is carried out. Actually these conditions are not fulfilled. Therefore the hypothesis of separatism has to be investigated. For Flanders, separatism economically offers more advantages than disadvantages. The budget equilibrium, the rates of interest, the social conditions and political stability would be improved, without the international solvability seriously affected.