In economics, the emergence of New Growth Theory in recent decades has directed attention to an old and important problem: what are the forces of economic growth and how can public policy enhance them? This book examines major forces of growth--including spillover effects and externalities, education and formation of human capital, knowledge creation through deliberate research efforts, and public infrastructure investment. Unique in emphasizing the importance of different forces for particular stages of development, it offers wide-ranging policy implications in the process.