Nan Lin's book *Social Capital: A Theory of Social Structure and Action* (2001) is a comprehensive and ambitious work that addresses the multifaceted concept of social capital. The book challenges the common criticism that the term "capital" is inappropriate for sociological use, arguing for the emergence of a new theory of capital (*neo-capital theory*) that includes concepts like human, cultural, and social capital. Lin defines social capital as the set of resources rooted in social networks that individuals can access and utilize in their actions. This definition is supported by the commonalities among various definitions proposed by different scholars. Lin emphasizes the importance of measuring social capital scientifically and positions it within rational choice theory. He argues that social capital is influenced by the social structure, particularly the stratification system, and that the success of an individual's actions depends on their position within this structure rather than their own status. The book outlines six postulates and twelve propositions to support these claims, focusing on the role of social networks in facilitating information flow, decision-making, trust, and identity. The empirical research conducted in China, involving 3,050 interviews, provides a practical framework for measuring social capital, distinguishing between general and political social capital. The second part of the book is more speculative, aiming to place social capital within a broader sociological theory that explains individual behavior and the emergence of social norms and structures. Lin's theory is grounded in the principle of minimizing losses, which he sees as crucial for optimizing decisions and maintaining social cohesion. Overall, Lin's work clarifies the concept of social capital and proposes a rigorous method for its measurement, making it a central element in a sociological theory of action and social structure.Nan Lin's book *Social Capital: A Theory of Social Structure and Action* (2001) is a comprehensive and ambitious work that addresses the multifaceted concept of social capital. The book challenges the common criticism that the term "capital" is inappropriate for sociological use, arguing for the emergence of a new theory of capital (*neo-capital theory*) that includes concepts like human, cultural, and social capital. Lin defines social capital as the set of resources rooted in social networks that individuals can access and utilize in their actions. This definition is supported by the commonalities among various definitions proposed by different scholars. Lin emphasizes the importance of measuring social capital scientifically and positions it within rational choice theory. He argues that social capital is influenced by the social structure, particularly the stratification system, and that the success of an individual's actions depends on their position within this structure rather than their own status. The book outlines six postulates and twelve propositions to support these claims, focusing on the role of social networks in facilitating information flow, decision-making, trust, and identity. The empirical research conducted in China, involving 3,050 interviews, provides a practical framework for measuring social capital, distinguishing between general and political social capital. The second part of the book is more speculative, aiming to place social capital within a broader sociological theory that explains individual behavior and the emergence of social norms and structures. Lin's theory is grounded in the principle of minimizing losses, which he sees as crucial for optimizing decisions and maintaining social cohesion. Overall, Lin's work clarifies the concept of social capital and proposes a rigorous method for its measurement, making it a central element in a sociological theory of action and social structure.