The notion of secularism has two dimensions: political and philosophical-ethical. Classically, the French conception refers mainly to the first (separation of church and state) and the Belgian conception to the second. However, recent developments show heated debates in France - on the philosophical and ethical levels - between "republican" and "liberal" secularism and, in Belgium, initiatives from the secular world at the political level: the wish to create a philosophy and citizenship course common to all, debates around the possible inclusion of the principle of secularism in the Constitution. The article puts into perspective the recent evolutions of secularism in the two countries.