This chapter examines the relationship between social participation and social capital in Italy, focusing on the role of non-profit institutions as infrastructures of civic engagement. Social capital is understood here as a relational resource grounded in networks of trust, reciprocity, and shared norms, which facilitate cooperation and contribute to social cohesion. Non-profit institutions are conceptualised as organisational arenas that may generate both bonding and bridging forms of social capital, although this potential is neither automatic nor uniform across contexts. The chapter highlights three key dimensions of complexity: (a) the coexistence of formal and informal modes of participation; (b) the partial decoupling between formal membership and feelings of belonging; and (c) the increasing proximity between non-profit and market-oriented logics. Empirically, the chapter analyses longitudinal and spatial data on the diffusion of non-profit organisations at national, regional, and provincial levels (2011–2021), drawing on ISTAT sources. The findings reveal persistent territorial disparities, particularly between Northern and Southern regions, while also documenting significant growth in several Southern provinces. These patterns suggest that non-profit development reflects broader socio-economic and institutional ecosystems rather than inherent civic dispositions. The chapter argues that understanding such dynamics is crucial for interpreting contemporary transformations in civic cultures.