Jessica Posner, the 23-year-old co-founder of Shining Hope for Communities, has been named the top world-changer among all Americans under the age of 25. Posner accepted her Do Something Award live on VH1, surrounded by celebrities (via The Denver Post). She rose to the top of five finalists, receiving the $100,000 prize for her organization, which opened the first free school for girls in Kibera, the largest slum on the African continent. Posner is also behind a gardening program, computer center, and environmentally friendly bathrooms. Next month, a community health center will be opened in Kibera by Shining Hope. "I am so grateful to receive this award on behalf of the Kibera community, because work is being done by so many more people than me," says Posner, "the girls in the school, their parents, and members of the community who are volunteering to build the health clinic." A long list of stars appeared at the event, from Megan Fox to George Lopez, notes a press release. Winners in other categories included Leonardo DiCaprio (Do Something Movie Star) and Hannah Teter (Do Something Athlete).