I present a collection of three essays exploring how firms in developing countries make supply-chain decisions and how those microeconomic decisions aggregate into macroeconomic outcomes. Chapter 1 In the first chapter, which is co-authored with Vasco Carvalho and Matthew Elliott, we consider how a firm’s position in a supply-chain can confer market power. We develop a tractable theory which introduces the notion of a bottleneck: a firm whose removal from the network leads to a sufficiently large fall in aggregate output such that supply can no longer meet demand. We develop a network algorithm to identify bottlenecks in an economy-wide production-network and apply these tools, at scale, in Uganda. We show that bottleneck firms have signif...