Brazilian cities are a laboratory for participatory democracy. The city of Porto Alegre, specially, is a symbol of grass-roots globalization because of Participatory Budgeting and the World Social Forum. Porto Alegre's Participatory Budgeting shifts the power to allocate part of the municipal's revenues from the City Council to public assemblies. More than three thousand municipalities worldwide experimented with Participatory Budgeting; this dissertation explores the long-term sustainability of this political institution in the city where it originated. How vulnerable are participatory institutions to partisan politics and market-forces? What are the circumstances under which the redistributive achievements of Participatory Budgeting become reversible? To answer these questions, I analyzed the past twenty years of Porto Alegre's expenditure budget to identify changes in the implementation of municipal services associated with changes in the political parties in power. With the same aim, I conducted archival research of previous Participatory Budgeting meeting minutes and verbatim transcriptions of deliberative meetings. I also collected narratives, oral histories, and surveys of Participatory Budgeting attendees. This dissertation is based on 18 months of participant observation of budgetary meetings and frequent fieldwork with grass-roots organizations that join in the process. Throughout this dissertation, I examine the transition of Porto Alegre's Participatory Budgeting from a mechanism of restraining some of the harshest manifestations of neoliberal urbanization to a model of urban development that privileges, largely, non-redistributive forms of urban planning. Each chapter addresses different but fundamental aspects of this transition and its outcomes in terms of redistributive justice, ideologies of participation and communicative practices, social values, personhood, and identity. Furthermore, I document the weakening of Participatory Budgeting, focusing on a new participatory project called the Local Solidarity Governance program. I analyze this transition from the point of view of those living in squatter settlements. I assess how effective Participatory Budgeting has been in housing the urban poor for its two decades of existence. Although political parties influence funding for housing, the design of Participatory Budgeting provides a bottom-up alternative to the either public housing or self-help policies of slum redevelopment by recognizing the diverse needs of people living in squatter settlements.