This monograph resurrects the spirit of classical economic thinking on network effects of division of labor and general equilibrium mechanisms that simultaneously determine the interdependent benefits of specialization and the number of participants in the network of division of labor (extent of the market) in a modern body of inframarginal economics. Inframarginal economics applies inframarginal analysis (nonclassical mathematical programming which allows corner solution) to studies of network effects of division of labor, individuals' networking decisions in choosing their levels of specialization, mechanisms that endogenously determine the network size and pattern of division of labor, increasing returns, and the relationship between transaction costs, evolution in institutions, property rights, contracts, organization, and the network size and pattern of division of labor. Here, inframarginal analysis is total cost-benefit analysis across different network patterns of trade and division of labor in addition to marginal analysis of resource allocation for a given pattern of organization. It provides an overarching framework that encompasses many areas of the discipline that have customarily been treated as separate branches. These include microeconomics, macroeconomics, development economics, international economics, urban economics, growth theory, industrial organization. applications of game theory in economics, economics of property rights, economics of transaction costs, economics of institutions and contracts, economics of organization, managerial economics, theory of hierarchy, new theory of the firm, theory of money, theory of insurance, theory of the network and reliability, and so on.