“Sociology and Isolation” explores historical foundations, cultural contexts, and contemporary implications of social isolation from a sociological perspective. Drawing on seminal works by early sociologists, this chapter highlights how social forces, such as capitalism, urbanization, and rationalization, contribute to individual isolation and disconnection from societal norms and integration. The discussion extends to the impact of historical events, such as the Spanish flu and the COVID-19 pandemic, which have exacerbated social isolation through public health measures and disruptions in social structures. Defining social isolation as a state of disconnection both physically and emotionally, emphasis is placed upon its significance for individual well-being, community cohesion, and broader societal dynamics. Various factors contributing to social isolation are examined, including demographic, economic, health-related, and structural influences. In this chapter, we differentiate between objective and subjective dimensions of isolation and explore intersectionality of social identities in relation to isolation and depression risk. The narrative underscores relationships between social isolation and depression, drawing on empirical research to demonstrate adverse mental health outcomes associated with social fractures and lack of social support.