Around the world, a rapidly increasing number of parliaments experiment with deliberative models allowing citizens to actively participate in public decision-making. Especially in Belgium, deliberative democracy appears to turn into a new form of democratic tradition. Since the innovative G1000, the country has progressed quickly on the subject. Within the last three years, the country has experienced a trend of institutionalisation as multiple parliaments within the federal system have permanently formalised deliberative mechanisms of citizen participation, namely the Parliament of the German-speaking Community, the Regional Parliament of the Brussels-Capital-Region as well as its components and the Regional Parliament of Wallonia. In this chapter we explore based on a ‘Three I approach’ why elected representatives choose to permanently cede autonomy by institutionalising deliberative citizen participation. We do so on the basis of interview data, observations and documentary data.