Executive Summary: 'One in four children, almost all of them living in developing countries, does not complete five years of basic education, and for every illiterate child there are eight adults who lack this fundamental coping skill. The regions of greatest risk are Sub-Saharan Africa and South Asia, and the situation is particularly bad for girls, who make up two-thirds of the world's unschooled children. Despite the daunting nature of the global education challenge, there are ample reasons for optimism. For one thing, we now know what works -politically, financially, and programmatically. Although millions of children have been left behind because of poverty, insufficient access, military conflict, and other forces, millions of others have been reached by highly effective education programs.'