This dissertation studies the effects of firm debt and financing frictions on the macroeconomy. Chapter 1 investigates the role of changes in firms' idiosyncratic risk and their cost of default in driving changes in employment and credit spreads, both over the business cycle and in the cross-section. I use firm-level panel data and a structural model of financial frictions and volatility shocks to assess the effects of shocks to firm volatility and default costs. I find that volatility shocks alone can only generate modest declines in aggregate employment. However, simultaneous shocks to firm volatility and default costs can interact to generate large employment declines. Chapter 2, co-authored with Robert Kurtzman, investigates the role of...