In the last decade there has been a revival of interest in economic growth, catch up, convergence and divergence. This work provides an analysis of these phenomena on a worldwide basis for the period since 1820. It provides the most comprehensive database available for comparative, quantitative analysis of the economic performance of nations. It contains the author's interpretation of the causal influences which have been operative in different phases of development and includes an extensive commentary on the analytical tools developed by economists in their attempts to explain variations in rates of growth and levels of income. This book is a sequel to the author's earlier volume The World Economy in the 20th Century.