A group of girls examine a rack of brightly colored prom dresses, laughing and talking. It’s a familiar scene during prom season—except that none of these dresses have price tags and they’re displayed not in a store, but in a balloon-festooned room at Ozone House on Washtenaw.

Ozone House is a nonprofit that provides temporary housing and other help to adolescents—and, once a year, organizes a “prom exchange.” (This year’s was being held on April 27 and 28.) Past prom-goers donate the nearly new clothes; sorority members have been particularly generous, says staff member Susan Kirtz. Ozone then gives the dresses to kids who might not have $75 or more to spend on a dress that’s worn only once.

At last year’s exchange, two Ypsilanti High School students, Shirley and ¬Keisha, looked critically at a black sequined strapless gown while surprisingly old-fashioned music—”As Time Goes By,” “There’s No Business Like Show Business”—played in the background. “The really nice ones are too expensive” at stores, said Shirley, who learned about the prom exchange through an announcement at school. Nearby, a Pioneer High student wearing a blue satin head scarf explained that she’d be going to the prom with a group of girls; because her religion forbids showing cleavage, she planned to cover her breasts with a shawl. Another girl with a head scarf, a Pioneer exchange student from Indonesia, was also looking at gowns. “Mom, what do you think?” she asked her American host mother.

By the time the three-hour shopping spree was over, forty kids left with gowns, shoes, or accessories such as scarves or hats. Twenty-five more attended a second exchange at Ozone’s drop-in center in Ypsilanti.

One of the teens shopping last year was obviously pregnant. To help keep prom night safe, Ozone House offers an additional gift: packages of individually wrapped, brightly colored condoms.