It's part social experiment, part video voyeurism. On MTV's "The Real World," seven attractive young people--a hodgepodge of races, genders and sexual orientations--live together for four months as a phalanx of cameras and microphones records their spats, romances and quasi-philosophical musings.

Now in its eighth season, "The Real World" is MTV's most popular program, with a weekly audience of 3.4 million viewers. It has spawned best-selling books, videos, Web sites, a college "lecture" tour and two TV spinoffs--"Road Rules" on MTV, and a forthcoming series on ABC that will track, "Real World"-style, a fledgling rock band.

The appeal? It's real, says co-creator Mary-Ellis Bunim. "All we have to do is stand back and let it happen," she says. "We're flies on the wall."

But much about "The Real World" is an illusion. Despite its documentary style and a slogan proclaiming that it's "as real as it gets," the series takes considerable license with reality.

People who have appeared on the series say it is heavily massaged to enhance excitement and encourage conflict--a manipulation that many of its loyal fans, admittedly, may not mind. Footage is often used out of sequence, distorting the timing of events. Some situations are made to look more dramatic through clever editing. Some aspects are stage-managed outright. When the "roommates" head off to volunteer at a youth center, the initiative comes not from the cast members themselves but from a producer's directive.

Real? In its earliest days, the show's producers actually scripted and directed interactions among the roommates, says Norm Korpi, who participated in the first season's chronicle, which took place in New York City. "They were very afraid there wouldn't be enough drama," said Korpi, the first gay man on the series. "They were very nervous about having a gay. The sponsors were nervous, too."

Korpi recalled that late one night during the filming, he and a fellow cast member sneaked into an off-limits production booth. "We found all these story lines laid out three weeks in advance," he said. "It said things like 'So-and-so will become involved with so-and-so,' 'So-and-so will audition for an acting job.' All these things to hype up the drama."

"Real World" co-creator Jon Murray, a documentary filmmaker, says Korpi merely found "outlines" of future episodes based on available footage. "He was never told what to say," Murray says.

Nevertheless, many of the program's production methods seem drawn more from the entertainment industry than from traditional documentary filmmaking. A staff of "writers" sifts through dozens of hours of footage to map out each week's 22-minute episode, complete with cliffhanger endings. Voice-overs and music are added in post-production to enhance dramatic moments. The roommates are interviewed on-camera to comment on themes selected by the writers. The soap-opera quality of the show may in part reflect co-creator Bunim's background; her TV production credits include the soaps "Search for Tomorrow" and "As the World Turns."

Janet Choi, who was on last season's "Real World," said some incidents depicted in the series were taken far out of context. During taping of her season's shows, for example, the cameras rolled as she shared meals with a male friend. "I had lunch with him maybe three times," said Choi, "and they made this whole romance episode out of it. They made it seem as if there was this hot and heavy thing going on. There really wasn't. There's a lot you can't control."

Rather than let reality take its course, the show's producers manufacture "missions" for the participants, such as having them host a fund-raiser for a youth organization during the current season in Hawaii. Last season in Seattle, the producers set the cast up as hosts of a show on a local radio station. During a previous season, the cast members were given $50,000 with which to start a business; they duly spent weeks discussing countless plans for the enterprise, which never got off the ground.

If all this proves insufficiently interesting, the cast is occasionally sent to an exotic locale, such as India or Kenya. A trip to Mount Everest last year produced a dramatic moment when Choi, a smoker, nearly passed out in the rarefied air.

The only "fantasy" element Bunim and Murray acknowledge is the well-appointed house or apartment the roommates share. This season, the action takes place in a $10,000-a-month beachfront house on Oahu, complete with a designer-made mini-volcano next to the private pool.

"I laugh and call it 'The Unreal World,' " says Jennifer Fox, a documentary filmmaker who lived with an interracial family for two years to make the recent PBS documentary series "An American Love Story." Documentarians typically set out to capture people and events as naturally as possible, she says, without interfering with the flow of events. The opposite is true on "The Real World," she adds: "They want extremes, they want people vying for as much [conflict] as they can get."

It's not clear if the show's devoted followers are aware of the stage-managing, or even if they care. Bunim and Murray think "Real World's" fans--most of whom are between 14 and 25--identify strongly with its themes: living away from home for the first time, sharing living space with others, making decisions for yourself.

Last week more than 2,000 people showed up at Towson University near Baltimore for a "Real World/Road Rules" speaking tour featuring former cast members. The mostly female crowd literally squealed with delight as the ex-roommates--"Montana, from Boston! . . . Justin, from Hawaii!"--were introduced.

"You see these people in a realistic tone, as they really are," said Towson freshman Kathleen Hertel. "It's not like 'Full House' or some other sitcom. It's definitely realistic."

Jill O'Hara, 32, a business consultant in Los Angeles, says she has watched the show for years. "You're getting a glimpse into people's lives," she says. "It's the drama of having a mix of people. It's not like acting. You feel like you're seeing someone's life playing out in front of you."

"Real World" certainly has its moments of unscripted spontaneity. The 1994 show captured the final months in the life of Pedro Zamora, an HIV-positive AIDS educator from San Francisco, who died just days after the season's last episode aired.

But "The Real World" can sometimes help "reality" along.

Several former cast members said their performances were so heavily edited that they were surprised by what they saw on TV. Irene McGee, from last season's series, recently told an interviewer: "I basically looked like I [was] insane. . . . I looked like a wack job on TV."

"I was upset about how they portrayed me," Korpi said. "The only thing they went after was sex. When I complained, the producers told me, 'Well, everything else was boring.' "

The characterizations and plot developments are typically worked out by the show's writers and editors, according to producers and cast members. Jason Cornwell saw both sides of the process as a cast member during the Boston season in 1996 and more recently as a "Real World" casting director and "Road Rules" writer.

To create a narrative flow, "we cut and paste" footage, Cornwell says. "Something that happens in Week 1 may appear in Week 6, and vice versa. That's where the reality is bent a bit. It's just a matter of using all the creative tools at your disposal."

Cornwell concedes that some kinds of reality won't make it onto the air. He says the show wouldn't air hate speech, espousals of extreme political positions, criticism of sponsors' products, or comments about the program itself.

Although the omnipresent camera crew isn't supposed to interact with cast members, there have been exceptions. In appearances around the country, Irene McGee, a former Georgetown University student who was also part of the Seattle cast, has described crew members moving her hands to expose the label on a bottle of Nantucket Nectar, which was supplying its product to the show.

In addition to romance, the program emphasizes squabbling among the roommates--and the seasons featuring the most notorious behavior have won the highest ratings. The disputes are usually verbal, but in one episode last season one of the roommates slapped McGee in the face after she insulted him.

This year, the central drama involves Ruthie Alcaide, a 21-year-old Rutgers University student. On her second night in the beach house, Alcaide passed out from drinking and had to be taken to the hospital to have her stomach pumped. Later, when she got behind the wheel of a car while intoxicated, the production crew warned her not to, but kept filming anyway as she drove off. The roommates eventually persuaded Alcaide to see a therapist--dutifully filmed--and pushed her to enroll in an alcohol treatment program.

Creators Murray and Bunim said they had no idea Alcaide had a drinking problem when they selected her. Although "Real World" does not seek participants with severe problems, the show thrives on conflict, Korpi says. "We were cast to not get along," he claims. "You can [then] edit in the drama. No one has to call you up and say, 'Call someone a bitch today.' "

The show's seven participants are chosen each year from among nearly 35,000 applicants, according to Murray. The process, which takes months, involves videotaping sessions and filling out personality profile questionnaires. Among other questions, applicants are asked, "What qualities or aspects of other people's behavior bother you the most?" "What is the best advice you have ever been given?" and "The thing that scares me most is . . . ." Applicants are extensively interviewed by casting directors who try to prod personal details from them and see how they react with others, said cast members.

Given that almost everyone who applies for the program has probably seen it already, documentary filmmaker Fox wonders if cast members really can keep it real.

The idea that you're making a TV program 24 hours a day probably does lead to camera-friendly antics, Cornwell concedes. "If you wanted to sit around all day and read a book, you could do that," he says. "But you're not going to get on TV doing that."

Sensitive to the notion that some cast members are playing to the camera, executive producer Bunim replies: "You can't sustain a character that isn't true to yourself, day and night, for 13 weeks. It's just not possible. It would drive you mad." While Bunim concedes that many roommates come to the show hoping it will launch their show business careers, she points out that very few have actually made that leap.

On the other hand, during the show's season in Los Angeles several years ago, one roommate did begin playing to the cameras. "Whenever she walked into a room, she'd turn to face the camera," recalls Murray. "The other cast members started calling her an actress. She was sort of acting like an actress."

Call it a case of reality imitating art imitating reality.

CAPTION: Reality check: MTV's "The Real World" supposedly depicts the actual lives of its cast members, seven of whom are chosen each season. But former participants say the show is tweaked to increase its drama.

CAPTION: Pedro Zamora, who later died of AIDS-related complications, in a 1994 episode of MTV's "The Real World."