Into the elegant stone mansion they came, sometimes alone, sometimes with friends, all members of what one called "the most elite sorority in the world." Women in tank tops, women in disco pants, women in short shorts, women in slit skirts, women in see-through dresses, women in tailored suits. Some were brassy, others nervous, many were stunning, others merely attractive. But for a brief time each and every one of them had reached a kind of popular culture pinnacle: Each had been a Playboy Playmate of the Month.

As part of that magazine's 25th anniversary celebration, Hugh Hefner, the panjandrum of Playboy, had sent out invitations to the 300-plus former playmates, asking them to gather for a weekend celebration in Los Angeles, all expenses paid. There would be parties, drawings for cars, TVs and other goodies, and a present from a grateful Hefner of a jeweled rabbit-head pendant for every playmate present and accounted for. "Without you," he told the asembled throng, "I'd have a literary magazine."

One hundred and thirty-six playmates responded to Hefner's call, one woman trekking all the way from Malta. A list of their post-playmate accomplishments was thoughtfully provided reporters, and it was no small comfort to learn for instance that Sue Bernard, Miss December 1966, is the author of "Joyous Motherhood," that Patty Reynolds, Miss September of 1965, is Illinois' only female naturalist, and that Bonnie Large, Miss March 1973, is, of all things, a "certified union hypnotist."

Hefner himself, dapper as ever in a three-piece suit despite the hotness of the day, was genuinely moved by what he called "a fantasy class reunion."

"I wasn't prepared for so much emotion. This is without question an event that will stay with me for as long as I like," he said. "When you think of how much the playmates have meant in the dreams and fantasies of American males, to have them all here in one room, it's sharing an experience that will not come again."

Equally overwhelmed as she surveyed the grandeur of the Playboy Mansion West was Janet Pilgrim, one of the magazine's original staff members and its only three-time playmate: July 1955, December 1955 and October 1956.

A striking woman of 45 who lives in Connecticut with her husband and two teen-age daughters. Pilgrim looked around at Hefner's pleasure dome and said, "It still amazes me. When I think of how we started, with tiny little offices in a tiny little building and only 13 people on the staff, I just can't believe it."

Pilgrim was not the first playmate, but she was the first of the girl-next-door types that were to win the magazine its enormous audience. "Hef was having trouble getting the kind of pinup pictures he wanted and all of a sudden someone said, just kind of a lark, 'Maybe we could send Janet to the photographer,'" she remembers.

The results of that lark included "a complete change in my attitude toward men and theirs toward me. Men thought if you were a playmate you were an easy mark. If a man asked me for a date and I knew he knew I'd been in the magazine, I almost always said no."

Still Pilgrim would not trade her playmate experiences. "I've had the opportunity to meet people and do things, things I'd never have been able to do otherwise," she says forcefully. "I probably would have been a dull little mailroom person punching the clock from 9 to 5 if this hadn't happened to me."

Expressing similar thought was another self-described "golden oldie," Eleanor Bradley, Miss February 1959. She too would do it all over again, but found that at the time "if we told people we were playmates we almost had to prove we weren't blithering idiots. Men thought we were made of cotton candy or something and we had to set an image that playmates weren't bad girls."

Although it shocked her friends and family, Bradley's pose is so discreet by today's standards that it could appear in Ladies' Home Journal. "Jesus, it was nothing, like walking around in a bikini," she says of her centerfold. "When I think of all the bad times I had, I could just kick myself."

If playmates have a bad time these days, they find, says Miki Garcia, Miss January 1973 and now director of Playmate Promotions, that the magazine still keeps a candle in the window for them.

"It's a paternalistic feeling, we're receptive to anything they may need -- a new portfolio, guidance as far as an upcoming movie goes, anything," she says. "Being a playmate is more than just a job, it's an experience like a sisterhood. If you meet another woman who's been a playmate you can start the conversation on another level, like guys saying 'Gee, I've been in the Air Force, too.'"

If the older generation of playmates were a bit timid about what they did, the newer ones seem to have no such qualms. No better example here than Vicki McCarty, Miss September 1979, a Phi Beta Kappa graduate of Berkeley, holder of an advanced law degree from Cambridge University, a student at Hastings College of Law and "a real nice person."

McCarty, 25, chose to be a playmate because "I'd been a serious student and a diligent young professional and I wanted a whole new facet to my life, a crazy experience." An added consideration was that playmates no longer get paid the $50 given to Janet Pilgrim. McCarty earned $10,000 for her photo sessions. She makes $300 a day when she does promotional work for the magazine and has had to fend off offers from California newspapers and TV stations since becoming a playmate.

"Being a playmate is almost a mythical thing, the magazine is a tradition," she explains. "I'm not subjected to any of the kind of treatment I would be if being a playmate were considered scandalous. It's just a little risque, and that's what I like about it."