"She looks the most beautiful when she's in the field – natural, no makeup, nothing," says Wyclef Jean of the actress-activist, 31. Indeed, her beauty needs are decidedly practical: a dusting of powder, a few strokes of mascara, a dab of Vaseline on her world-famous lips and – voilà! – she's ready to meet the president of Pakistan. "She wants to make a difference," says U.N. representative Guebre-Christos. "She does it with a lot of simplicity."