The purpose of this publication is to highlight the development challenges faced by people who live in drylands and to outline how these challenges can be tackled successfully. Covering about 40 percent of the world’s land surface, dryland is home to more than 2 billion people in nearly 100 countries, of which about half remains under poverty. It will be impossible to meet the Millennium Development Goals by 2015 if life does not improve for the poor people of the drylands. Together, they are the forgotten billion. The publication stresses that the policies designed to meet the needs of dryland peoples must be based on a sound understanding of the full complexity and dynamics of dryland ecosystems. They need to emphasize the value of dryland ecosystem services and the investment and marketing opportunities they offer.