Nan Lin's *Social Capital: A Theory of Social Structure and Action* (2001) is a comprehensive exploration of the concept of social capital, which goes beyond its title to present a theoretical framework that integrates social structure and individual action. Lin challenges the criticism that the term "capital" is inappropriate in sociological theory, arguing that a new neo-capital theory has emerged, which replaces class-based analysis with concepts such as human, cultural, and social capital. Lin defines social capital as the resources embedded in social networks that individuals can access and use in their actions. He emphasizes that social capital is measurable and aligns with rational choice theory. Lin's analysis of social structure is hierarchical, with individuals' social capital depending on the positions of their network members within the stratification system. He argues that the success of an individual's action is more influenced by the positions of their social connections than their own position. He outlines six principles and twelve propositions that explain how social capital functions within social networks, emphasizing the strength of ties, proximity to bridges connecting different social systems, and the role of social hierarchy. Lin's empirical research in China, involving 3,050 individuals, provides a practical instrument for measuring social capital, distinguishing between general and political social capital. The book's first part is theoretical, while the second part is more speculative, aiming to place social capital within a broader sociological theory that explains individual behavior and the emergence of norms and structures. Lin's theory is grounded in the principle of minimizing resource loss, which he argues is more fundamental than maximizing gains. This principle underpins the necessity of loyalty to social groups and the transformation of individual resources into collective ones. Lin's work contributes to the field by clarifying the concept of social capital, proposing a rigorous measurement framework, and positioning it as central to social action and normative structures. It bridges micro and macro sociological perspectives, offering a unique contribution to the tradition of sociological theory based on rational choice axioms.Nan Lin's *Social Capital: A Theory of Social Structure and Action* (2001) is a comprehensive exploration of the concept of social capital, which goes beyond its title to present a theoretical framework that integrates social structure and individual action. Lin challenges the criticism that the term "capital" is inappropriate in sociological theory, arguing that a new neo-capital theory has emerged, which replaces class-based analysis with concepts such as human, cultural, and social capital. Lin defines social capital as the resources embedded in social networks that individuals can access and use in their actions. He emphasizes that social capital is measurable and aligns with rational choice theory. Lin's analysis of social structure is hierarchical, with individuals' social capital depending on the positions of their network members within the stratification system. He argues that the success of an individual's action is more influenced by the positions of their social connections than their own position. He outlines six principles and twelve propositions that explain how social capital functions within social networks, emphasizing the strength of ties, proximity to bridges connecting different social systems, and the role of social hierarchy. Lin's empirical research in China, involving 3,050 individuals, provides a practical instrument for measuring social capital, distinguishing between general and political social capital. The book's first part is theoretical, while the second part is more speculative, aiming to place social capital within a broader sociological theory that explains individual behavior and the emergence of norms and structures. Lin's theory is grounded in the principle of minimizing resource loss, which he argues is more fundamental than maximizing gains. This principle underpins the necessity of loyalty to social groups and the transformation of individual resources into collective ones. Lin's work contributes to the field by clarifying the concept of social capital, proposing a rigorous measurement framework, and positioning it as central to social action and normative structures. It bridges micro and macro sociological perspectives, offering a unique contribution to the tradition of sociological theory based on rational choice axioms.