Adolescent girls in poor countries play pivotal - but often overlooked - roles in their families and communities. Each day they cook, clean, fetch water, do agricultural work, and care for children and the elderly, which frees up time for other family members to work and earn money. But providing these services comes at huge costs to the girls themselves - and to theire families and eventualy to future generations - because denying opportunities to girls prevents them from reaching their full potential.

We know much more about those costs now than we did 10 or 20 years ago: Many girls have no say in major life decisions. Family and community norms often harm their well-being and their transitions to adulthood. Girls marry and have children at young ages, often against their will. Violence is common-place, impairing their health and schooling. Economic opportunities outside the household are rare.