This article characterizes the political and coalitional system in Belgian federal governments. It underlines the ways governmental coalitions function and their impact on public policy design and implementation as well as on the law-making process. Based on a veto players analysis (which refers to the institutional and partisan actors whose agreement is required to change a policy), it also considers the institutionalization of the political practices facilitating the reaching of an agreement. The rules of the political game, which have been progressively formalized by actors, not only influence the capacity to implement reforms, but above all the choice of the procedures mobilized and selection among diverse alternatives. In Belgium, those rules reveal the tensions between coalitional constraints and compromises necessary to overcome the disagreements between parties and linguistic groups.