Despite the strong theoretical expectations about the beneficial effect of direct democratic instruments on citizens’ political support, the empirical evidence is scarce and inconsistent. We add to this literature by studying the effect of the use of a direct democratic process on citizens’ political support and its underlying causal mechanism. Using a unique research design that combines a strong test of causality with a high level of ecological validity, we surveyed inhabitants of a Belgian neighborhood that held a local referendum and a comparison group (i.e. inhabitants of a comparable neighborhood without referendum) before and after the referendum (n = 1049). Using difference-in-differences analysis and first difference regression analysis, we show that in line with our expectations the increase in political support following the referendum is not driven by involvement or procedural fairness perceptions but by an increase in support levels among the winners of the decision. Moreover, despite the contested nature of the issue, losers’ level of political support did not decrease significantly after the result of the referendum was announced.