Science in the developing world has experienced historic change over the past 30 years. Nations that lacked resources for even basic science have since developed world-class research centres. Men and women who previously had no chance of pursuing scientific careers in their own countries now thrive in home-grown universities and laboratories dedicated to scientific excellence.The World Academy of Sciences (TWAS) has been front and centre during this remarkable transformation. A Voice for Science in the South tells the story of TWAS through the eyes of 11 eminent scientists associated with the Academy. They speak of the organization's challenges and triumphs, and describe what TWAS has meant for their careers and the careers of thousands of scientists in the developing world. They also explore the challenges that lie ahead for TWAS and, more generally, for science in the South. It is a story of unprecedented global change and an account of what must be done to ensure that all nations can share in the benefits that emerge when science is woven into the fabric of society.