We develop a framework that uses micro data to estimate the aggregate capital-labor elasticity of substitution. We first show that the aggregate elasticity is a convex combination of the plant-level elasticity of substitution and the elasticity of demand. This expression captures substitution...

This paper studies an environment in which the network structure of production - who buys inputs from whom - is determined endogenously and is the key determinant of aggregate productivity. I address two questions: How do contracting frictions shape the equilibrium network structure? And...