‘Why are some countries rich and others poor?’ considers various theories of economic growth, including Robert Solow’s widely used 1956 model, and charts the uneven development of countries around the world from the late nineteenth century, through the twentieth century, and into the twenty-first century. Some countries, such as Japan and South Korea, have seen miraculous economic growth, whereas countries such as Argentina and Uruguay have not experienced expected levels of growth. The factors that affect development trajectories include natural resource endowments, geography, history, institutions, politics, and power. While overall levels of poverty have declined, levels of inequality are rising in almost all countries.