The aim of this article is to provide some historical insights about the origins of the three traditional Belgian politica[ families (the catholic, the liberal and the socialist) from the independance of the country to 1914. It shows the dynamic of a growing institutional stratification, due to the competition between the different families, trying to take the popular masses in charge, or by manipulation or by self representation. By that way, this research does put the historical basis of the problem of the movement for the fusion of the «progressists» and the trade unions fronts.