They’ve been deployed to Sudan, Kosovo, and the West Bank, to churchyards, soccer fields, and refugee camps—anywhere that people in crisis can gather. They are not soldiers or NGO workers or U.N. emissaries. They are clowns. And though the front lines of violent conflict are often mere miles away, they stand before crowds of children—armed with only a keen sense of physical humor—and try to make them smile.

Since 1993, Clowns Without Borders has made a mission of sending some of the world’s best mimes, jugglers, and puppeteers into some of the world’s most unhappy places. “Humor isn’t only about laughter,” says Mr. Yoowho (Moshe Cohen), the executive director of the U.S. chapter. “It can offer moments of joy and celebration in places where that’s not always available.”