When a girl becomes pregnant, her present and future change radically, and rarely for the better. Pregnancy before a girl is physically, developmentally and socially ready jeopardizes her right to a safe, successful transition into adulthood. This publication presents strategic thinking and reviews the best available evidence on effective    strategies and interventions to empower girls and reduce their vulnerability to adolescent pregnancy. Drawing from the evaluated evidence, it provides guidance on how to implement effective programmes that operate at multiple levels and with multiple stakeholders, including and most importantly, with the adolescent girl.