In the future Belgian State, in which «communities» and «regions» are constitutionally authorized, the composition, the mission and the competences of the second Chamber, the Senate, are called in question. The «community-agreements» of Egmont and Stuyvenberg provided that the members of the regional councils should be also members of the councils of the communities and members of a Senate (of communities and regions). His legislative roll should be limited to pass the revision of the Constitution, the bills with a special majority and to propose amendments at the bills to the Chamber of deputies. The second Chamber, in the European states, envisaged by this study: the French Senate, the Italian Senate, the German Bundesrat and the Swiss Council of States, is always more powerfull that a simple Chamber of reflection, at least on the legislative ground, in the federal states, this assembly has not immediate political control on the national Government. The future Belgian Senate, as these second Chambers, must preserve an active roll in the elaboration of the most important laws and be an assembly of beneficial confrontation between the communities and their deputies; so, the Senate will assure their effective participation to the legislàtîve function.