Participatory budgeting (PB) has been one of the most popular local democratic reforms in Latin America in recent decades. This article examines what happened to PB when it was scaled up to the state level and integrated in a participatory system in Rio Grande do Sul, Brazil (2011–14). Using theories of deliberative systems, multichannel participation, ‘venue shopping’ (the practice of seeking the most favourable policy venue) and countervailing power, as well as a multimethod research design, we explain how the systems approach allowed for both deliberation and direct democracy and mobilised new sectors to participate online. However, on the negative side, the different participation channels undermined each other. Social movements migrated to other spaces, leaving the budgeting process open to control by well-established, powerful public-sector groups.