Williams is the daughter of a Vermont county judge and a mother who oversees housing projects. After earning a degree from the Johns Hopkins School of Advanced International Studies, she began her career as an activist, protesting U.S. policy in Central America in the early 1980s. Eventually she became the associate director of the Los Angeles-based humanitarian relief organization Medical Aid to El Salvador.
Williams was hired by the Vietnam Veterans of America Foundation in 1991 to form an anti-land mine coalition. "When we began, we were just three people sitting in a room," she said. "It was Utopia." The numbers grew quickly. The fruits of her labor resulted in the ICBL, an alliance of more than 1,000 anti-land mine groups. Early on, a participant predicted that it would take at least 30 years for a land-mine ban to be enacted.
Previously, she taught English as a Second Language (ESL) in Mexico, the United Kingdom, and Washington, D.C. She lives in Vermont, where she was born in 1950.