The 2010 TIME 100

With his abiding compassion for the rural poor in his native India, Sanjit "Bunker" Roy, 64, has nurtured a grass-roots social entrepreneurship that is redefining the way the world thinks about fighting poverty.

Roy's Barefoot College has trained more than 3 million people for jobs in the modern world, in buildings so rudimentary they have dirt floors and no chairs. This bottom-up approach is designed to make poor students feel comfortable. The college's "barefoot professionals" then return home to use their new skills — as solar engineers, teachers, midwives, weavers, architects, doctors and more.

Roy combines humanitarianism, entrepreneurship and education to help people steer their own path out of poverty, fostering dignity and self-determination along the way. His simple formula holds a key to what nations and aid organizations might do to build a more just world.

Mortenson is the best-selling author of Three Cups of Tea and Stones into Schools

TIME 100 Social-Networking Index: 0

Correction appended: April 30, 2010. The original version of this article misidentified Roy's age as 50. He is 64.