This book addresses systematically and quantitatively the role of educational attainment in global population trends and models. Six background chapters summarize past trends in fertility, mortality, migration, and education; examine relevant theories and identify key determining factors; and set the assumptions that are subsequently translated into alternative scenario projections to 2100. These assumptions derive from a global survey of hundreds of experts and five expert meetings on as many continents. Another chapter details their translation into multi-dimensional projections by age, sex, and level of education. The book's final chapters analyse the results, emphasizing alternative trends in human capital, new ways of studying ageing and the quantification of alternative population, and education pathways in the context of global sustainable development. An appendix and associated web link present detailed results for all countries. The book shows that adding education to age and sex substantially alters the way we see the future.