Introduction -- Networks : concepts and empirics -- Games on networks -- Coordination and cooperation -- Social learning -- Social networks in labor markets -- Strategic network formation : concepts -- One-sided link formation -- Two-sided link formation -- Research collaboration among firms

Ramsey equilibrium models with heterogeneous agents and borrowing constraints are shown to yield efficient equilibrium sequences of aggregate capital and consumption. The proof of this result is based on verifying that equilibrium sequences of prices satisfy the Malinvaud criterion for efficiency.