What part does technological knowledge accumulation play in modern economic growth? This book investigates and examines the predictions of new growth theory, using OECD manufacturing data. Its empirical findings portray a novel and complex picture of the features of long-term growth, where technological knowledge production and diffusion play a central part, alongside variations in capital and employment. A parallel examination of long-run trade patterns and government policy issues completes a broader account of how knowledge-based growth in industrial output is at the heart of modern economic prosperity.