This book analyzes the dynamic macroeconomic effects of public capital in industrialized countries. The issue of whether public capital is productive has received a great deal of recent attention. Yet, existing empirical analyses have been limited to a small set of countries. This book presents a new database that provides internationally comparable capital stock estimates for 22 OECD countries for the 1960-2001 period. Building on this database, the book estimates the dynamic effects of public capital using a variety of econometric methods. The results suggest that public capital is productive in OECD countries on average. The theoretical analysis based on a dynamic general equilibrium model shows that the effects of public capital depend crucially on the way the government chooses to finance additional spending.