The first time, they say, is the toughest. "I was really nervous," says Christina Ricci, who stripped down for a scene in Prozac Nation (due in March). "I made [costar] Michelle Williams sit by the monitor and tell me, like, 'Ooh, sit up.' 'Ooh, put your arm back there so you look better.' But after a while it was like, 'I'm totally naked and I'm not supposed to be.' It's sort of liberating."

Welcome to the party. Thirty years after Last Tango in Paris shocked audiences with its full-frontal nudity and explicit sexuality, skin is well and truly in. In this year alone, five of the Oscar nominees for Best Actress and Best Supporting Actress—Halle Berry, Nicole Kidman, Kate Winslet, Sissy Spacek and Helen Mirren—had at one time or another stripped naked for a part. George Clooney bares his behind for the thriller Solaris. And R-rated films like Red Dragon, Unfaithful and Monster's Ball have caused barely a shrug for their nude scenes while raking in healthy sums at the box office. All, of course, in the name of realism. As Unfaithful star Diane Lane puts it, "You can't tell a story about infidelity without [it]...how can you have a hamburger without any meat?"

For young actresses the question may be, How can you expect to have a career? "They see [nudity] as a way into the business," says New York Daily News film critic Jami Bernard, author of Total Exposure: The Movie Buff's Guide to Celebrity Nude Scenes. "After Sharon Stone did the leg-crossing scene in Basic Instinct, she was offered Casino with Scorsese." And for actresses of a certain age, she adds, "nudity keeps audiences thinking you are sexy. Otherwise they start offering you the Driving Miss Daisy parts." Regrets, if any, come after the paycheck is cashed. Selma Blair, 30, felt fine about her torrid love scene with Robert Wisdom in the small movie Storytelling until she considered her audience. "I don't know how I'll take my mom to it," she said at the time.

Plenty of moviegoers think like Mom. "People are tired of gratuitous nudity," insists Elayne Blythe, president of the Hollywood-based Film Advisory Board, which gives its seal of approval to movies it finds suitable for family viewing. "Bogart and Bacall or Tracy and Hepburn are sexier with their clothes on than [today's stars] are with their clothes off." Tell that to the accounting department. "It's all about money," says British casting director John Hubbard (Lord of the Rings). "Any people you can get in to see Halle Berry's breasts, that's money."

Brad Pitt's nether regions? That's another thing: Full-frontal male nudity is the last taboo. Even '97's Full Monty fell short of its title. "When you have men fully naked, heterosexual men get squeamish watching it," says author Bernard. "That's why Hollywood has kept away from it." Not that actors shy away. Ewan McGregor has demonstrated enthusiasm for dropping his drawers, most notoriously in 1998's Velvet Goldmine. "In real life you don't get up with the sheet after you've had sex," he says.

At the other end of the modesty spectrum, stars like Julia Roberts, Sarah Michelle Gellar and Sarah Jessica Parker insert clauses in their contracts dictating down to the inch how much can be revealed. "I simply don't feel comfortable taking my clothes off," Parker told the Los Angeles Daily News. As Roberts has put it: "When you act with your clothes on, it's a performance. When you act with your clothes off, it's a documentary. I don't do documentaries." Kathy Bates agreed to go bare in a hot-tub scene with Jack Nicholson in Dec. 13's About Schmidt, but only after intense negotiations. "I'd say, 'I'll show this but I won't show that,' " she says. "It was fun, actually. When I was getting out and putting my robe on, Jack walked up to me and shook my hand and said, 'Beautiful work, honey.' I thought that was great."

Contracts aren't the only cover: A spare sock for men and patches for women are staples on sets. And just in case, some actresses put black electrical tape on their breasts so that camera operators won't shoot what they're not supposed to. "If there are parts of you that you don't want to have the crew see," advises Geena Davis, "make sure it's really visible."

When all else fails, there's always the body double. But even that option isn't entirely blush-free. "Choosing a double is a little embarrassing," says Angela Bassett. "Women come parading through, and there they are baring it all, and you have to say, 'Okay, can you turn around now?' and you're just checking them out." It's enough hassle for some actors to say the hell with it and strip. "I used to say, 'No, no, no,' but I think now if the role required it, I'd agree," says Lela Rochon. "Then I'd starve myself to death and hire three trainers."

Julie K.L. Dam with bureau reports