Alleviating poverty is more guesswork than science, and lack of data on aid's impact raises questions about how to provide it. But Clark Medal-winner Esther Duflo says it's possible to know which development efforts help and which hurt—by testing solutions with randomized trials. 

Nathan Myhrvold and team's latest inventions—as brilliant as they are bold—remind us that the world needs wild creativity to tackle big problems like malaria. And just as that idea sinks in, he rolls out a live demo of a new, mosquito-zapping gizmo you have to see to believe. 

At age 14, in poverty and famine, a Malawian boy built a windmill to power his family's home. At age 22, William Kamkwamba spoke at TED for the second time, sharing in his own words the moving tale of invention that changed his life.

At TEDxChange, Melinda Gates makes a provocative case for nonprofits taking a cue from corporations such as Coca-Cola, whose plugged-in, global network of marketers and distributors ensures that every remote village wants—and can get—a Coke. Why shouldn't this work for condoms, sanitation, vaccinations too?

Virus hunter Nathan Wolfe is outwitting the next pandemic by staying two steps ahead: discovering deadly new viruses where they first emerge (passing from animals to humans among poor subsistence hunters in Africa) before they claim millions of lives.

Our lives, our cultures, are composed of many overlapping stories. Novelist Chimamanda Adichie tells the story of how she found her authentic cultural voice—and warns that if we hear only a single story about another person or country, we risk a critical misunderstanding.