Eighteen-year-old Lauren Tomasik had a vision. This Wheaton Academy senior wanted to see her Christian high school raise $75,000 to build a medical clinic in Zambia to combat HIV/AIDS. And she wanted the money to come from the pockets of her 575 fellow students.

This was no ordinary vision. But lately this had been no ordinary school, considering that in the past three years these students in Chicago's western suburbs raised nearly $250,000 for HIV/AIDS relief in Africa. Most of it came out of their own pockets.

"God has called this school to do this project," said Tomasik, describing a student body whose members encourage each other to forgo movies, Starbucks runs, and even Christmas presents and prom dresses in order to use that money to provide Zambian peers with education and food. "Living in Wheaton, it's so easy to be focused on your own needs and live in the Wheaton bubble," she said of life in her affluent town, well known for its evangelical subculture. "But I have been blessed so that I can bless others."

Few might expect to find simplicity, sacrifice, and compassion among teenagers. "To me, these are difficult things for a Christian suburban teenager to grasp," said Academy chaplain Chip Huber. "We are a blessed people on our campus, no doubt about it. But instead of soaking it up, we're doing something—taking our faith and making it active."

The story that transformed an upper-middle-class high school into a model for sacrificial giving began on a retreat in the Colorado mountains in summer 2002. Student leaders gathered to plan how to guide their campus spiritually that school year. They tossed around familiar ideas—prayer groups and breakfasts. Something was lacking.

"We knew what was ...