This chapter explores the relationship between social sustainability and social capital within the broader framework of sustainable development. Social sustainability emerged later than environmental and economic dimensions, developing from early concerns about human-ecosystem interactions to a multidimensional approach integrating social, economic, and environmental aspects. The concept has evolved significantly since the 1980s, moving from a complementary role to economic and environmental development to becoming an autonomous dimension. Social capital emerges as a crucial component within the social sustainability framework, particularly in its bridging dimension related to solidarity and cooperation practices. The chapter concludes that while the semantic breadth of social sustainability allows for comprehensive understanding of contemporary social challenges, it risks conceptual indeterminacy.