This paper explores the intricate dynamics of urban conflicts and public spaces, focusing on the tension between participation and representation in grassroots mobilizations. Using an emblematic case study from Milan, the research examines how local committees navigate disputes over urban space allocation while addressing divergent interests among residents, public authorities, and organized groups. How do local mobilizations balance participation and representation in the contestation of public space governance, and what are the implications for democratic legitimacy and urban planning? Drawing on theories of public space (Boltanski and Thévenot, 2006), civic participation (Della Porta, 2004), and normative conflict (Hirschman, 1991), the paper situates the study within broader debates on governance, justice, and urban sociology. It highlights the "grammar of public justification" as a central mechanism through which actors legitimize their claims. The research employs a mixed-method approach, including historical analysis, participant observation, and in-depth interviews. A detailed reconstruction of a 30-year-long conflict over a contested urban area in Milan provides the empirical basis for this study. The analysis incorporates archival data, interviews with committee members and residents, and ethnographic observation of public meetings and neighborhood interactions. Historical Context and Mobilization Dynamics: The first section traces the origins of the conflict surrounding the Colombo Park. It examines the emergence of grassroots mobilization, initial protests, and the evolving demands of local committees, highlighting how these shaped the public debate on urban green space. Participation versus Representation: This section delves into the tension between inclusive participation and selective representation. It critiques the self-appointment of committees as representatives of residents without securing explicit legitimacy, revealing fractures in their claims to democratic accountability. The Role of Material and Symbolic Stakes: The study explores the symbolic and material dimensions of urban green spaces, particularly the contentious inclusion of an amphitheater in the park's design. It analyzes how residents' fears of degradation and safety shaped their resistance to the project, despite its collective benefits. Conflict, Compromise, and Democratic Deficits: The final section assesses the broader implications of the conflict for participatory governance. It discusses the limitations of participatory processes that fail to integrate diverse voices, leading to fragmented outcomes and reinforcing public distrust. The paper argues that urban conflicts, such as the one studied, reveal critical challenges in contemporary participatory governance. It underscores the importance of institutional mediation to reconcile competing claims and foster a shared sense of the public good. The study calls for more inclusive and iterative participatory frameworks to address the inherent tensions between collective aspirations and individual concerns.