Fashion Week parties -- A day-by-day wrap-up of which celebrities, from Leonardo DiCaprio to Naomi Campbell and Iman, showed up

If celebrated Washington, D.C., hostess Sally Quinn is right about every party being like a study in anthropology, then the most recent Fashion Week yielded some of the most important discoveries about the celebrity-fashion axis since the rise of the supermodel.

Due to a fortuitous calendar confluence, this fall’s event — one of the twice-yearly U.S. previews of designer duds — coincided with Halloween, a few movie premieres (Meet Joe Black, The Waterboy), a store opening, four book parties, and at least one birthday bash (hint: His name rhymes with Buffy). Not only did that turn the nights of Oct. 31-Nov. 5 into some of the most star-studded in New York City history, it also opened a new chapter in couture’s courtship of Hollywood.

Fashion types usually rule the Week, with celebs merely decorating the shows’ front rows. This time, however, celebs took charge. So the chic but utilitarian clothes (like silk cargo pants) were mere diversions amid the flurry of chauffeured limos, cell phones, and those all-important invites. Herewith, a diary of who ate, drank, and didn’t behave themselves.

Saturday, October 31
Parties 4 | # of Costume Changes by Mariah Carey 2 | Leo Sightings 3 | Note to self: Program cell-phone speed dial

Ending up at the wrong party tonight seems a fate worse than getting second billing to Billy Zane. Obviously, Russell Simmons’ 8 p.m. runway show for his Phat Farm clothing line is a must, if only to find out where everyone is going later. Donald Trump, sitting with his arm candy this evening, model Melania Knauss, says he’s hitting Mariah’s bash at Puffy Combs’ restaurant, Justin’s (hmm, worth checking out, just to see how small her outfit is); Interscope Records honcho Ted Field’s party in SoHo (considering he’s just visiting from L.A., this one has surprising buzz); and Tommy Mottola’s Sony Music soiree at Shine (never been there, but isn’t that one of Leo’s hangouts?). Still, Rush Hour director Brett Ratner thinks Tommy’s party may be the one to skip. ”It will be all suits,” he says, before heading to dinner at Moomba — celeb central these days — with pal Stephen Dorff.

At 11 p.m., it’s time to start working the phone. ”Everyone is calling each other, checking in if it’s the right party they’re at, or if they should leave and go to another one,” observes Lara Shriftman, 27, a well-connected publicist (she pitches for Motorola) who’s dressed in a cowboy hat as Charlene Tilton.

By midnight, a friend calls to report that the velvet rope at Ted Field’s is a mob scene; don’t even try it. Good thing Mariah’s party is picking up steam. Ashley Judd’s there, dressed as an angel. Puffy’s trying his best to be incognito in a Scream mask, but his ostentatious diamond watch gives him away. And Mariah, in a skimpy lamb costume (she later dresses as CHiPs‘ Erik Estrada), doesn’t disappoint.

But — ring! ring! ring! — it sounds like the real scene is over at Lot 61, the cavernous Chelsea restaurant where professional boy-about-town Donovan Leitch, and his model wife, Kirsty Hume, are throwing their own costumed revel. Hume and her super-twig friends are made up as geisha girls. Oliver Stone is Zorro (Antonio Banderas needn’t worry). But Kevin Costner — subtract 10 points — shows up without a costume. ”I said, ‘You can only come in if you come in as Kevin Costner.’ So he did,” needles Leitch.

However, the defining moment belongs to Leonardo DiCaprio, who has his first brush with anonymity in more than a year. Decked out in Kiss masks, he and three members of his posse (including actor Lukas Haas) arrive at Lot 61 and discover what it’s like to be on the other side of the rope. ”The doormen didn’t know who he was, and he said he couldn’t reveal who he was,” says Leitch. The foursome — who also caroused at Shine and Moomba — get in anyway. ”They were really acting out of control, jumping around on things and whooping it up,” adds Leitch, ”and I was like, ‘Can we get these Kiss jokers out of here?”’