In comparison with neighbouring countries, the peri-urbanisation process in Belgium is very important in many aspects. In relation with sustainable development strategic objectives, this is a major issue and numerous researches have shown that peri-urbanisation contributes to various collective costs. By comparing Belgium with the situation in Denmark and in Switzerland, two countries renowned for their relatively effective urban containment, the aim of this paper is to analyse why sprawl so deeply affects the Belgian territory. Three issues are taken into account for this comparison: land policy, housing development and the Belgian choice for car mobility. This triple analysis shows that peri-urbanisation processes are deeply implanted in Belgium. They are indeed related with the influence of natural environment, with old reticence for urban life, with a weak consciousness towards planning and with persistent political choices in favour of centrifugal dynamics.