Most of the analysis of inclusive democratic processes focuses on the quality of public deliberation or on inclusion effects on social capital. This paper examines the impact of inclusive processes on the political system, aiming at providing a preliminary answer to the question "what happens when citizens decide?". The paper uses a broad systemic perspective to analyze three Italian experiences of participatory budgeting at the local level. The analysis leads to some conclusions about the impact of participatory budgeting on "input" (citizens' demands, building of the political agenda), "outputs" (public policies) and "feedbacks" (reactions and responses of civil society).