Most communities are content to raise school funds the old-fashioned way, but bake sales and bazaars just won't do for New York City's fashion elite. Swapping brownies for burlesque, Zac Posen and sister Alexandra hosted a raucous bash Tuesday night in honor of Teachers Count—a nonprofit dedicated to helping the academic field. Guests ogled silent-auction items, such as a David Yurman bracelet and a Tory Burch bag, and were captivated by the hour-long show of five different acts, ranging from tantric yoga to something called the Bored Whore. Proud mama Susan Posen was unruffled by the performance's racy nature; also no cause for alarm was the designer's better-late-than-never appearance with constant companion (and honorary chair) Claire Danes. Noting her son's arrival, Posen said, "This is fun…and it's about to get better!"

The event, which raised roughly $100,000 for the charity, drew Posen-clad patrons including Theodora and Alexandra Richards, Fabiola Beracasa, and Tinsley Mortimer, as well as eighties icon Ally Sheedy, who spent most of the night barefoot on the dance floor. "I met Zac, and he asked me to come," she said between sets. "He gave me two dresses: one for tonight and another that I'm wearing to the MTV Movie Awards." Then Van Halen's "Jump" started up, and she dashed back to the floor, exclaiming, "I have to dance to this!"

—Sarah Cristobal