Brazil has been a fertile place for successful democratic innovations since its re-democratization in the 1980s, ranging from local Participatory Budgeting up to more complex forms of Participatory Systems at different government levels. The left leaning Workers’ Party(PT) has had a prominent role in such diffusion process. But why? I argue that the promotion of participatory institutions by PT is a combination of ideological and pragmatic interests. Ideologically, PT forges its political identity in mutual constitution with grassroots social movements and a strong commitment with redistributive policies. On the pragmatic side, the multiplication of State-Society interaction channels enables the building of a social coalition to support the government and its political agenda, in a complex governance arrangement. My argument is based on in-depth process tracing, which compares two different government levels: the State of Rio Grande do Sul and the Brazilian Federal Government, between 1999 and 2014.