Here's what's happening in New York City.
Barneys New York: The retailer is hosting an open-to-all karaoke contest, judged by Mary-Kate and Ashley Olsen and Proenza Schouler's Lazaro Hernandez and Jack McCollough.
Daphne Guinness will promote her new Daphne fragrance, and the designers behind Rag & Bone and Shipley & Halmos will play in a doubles ping-pong tournament against fans and customers.
Bergdorf Goodman: Celebrities and designers such as Victoria Beckham, Nicole Richie, Tom Ford, Mary J. Blige, Jason Wu, and Thom Browne will stop by, in addition to a dog fashion show featuring Marchesa's Georgina Chapman, Thakoon Panichgul, James Mischka and Mark Badgley, Reem Acra, and Lela Rose walking the catwalk with their pups.
Catherine Malandrino, Trish McEvoy, Vogue's Hamish Bowles, and blogger Bryanboy will serve as judges for a Face-Off Makeup Artist Competition, and there'll be complimentary beauty treatments and -- like Barneys -- a little karaoke hosted by Patrick McMullan.
Macy's Herald Square: Jessica Simpson will meet fans, as will Oscar de la Renta, Joss Stone, and Rachel Roy, who will help style customers in her Rachel Rachel Roy line before a live photo shoot and chance for shoppers to appear in her Fall 2010 look book. Just outside the iconic store, Tommy Hilfiger will host a fashionable tailgate party à la his new ad campaign.
Saks Fifth Avenue: The retailer is holding a rock-and-roll-themed event complete with fashion show, makeup lessons, and appearances by Donna Karan, Zac Posen, Viktor Horsting and Rolf Snoeren of Viktor & Rolf, Chris Benz, Charlotte Ronson, Brian Reyes, Tom Pecheux, Frederic Fekkai, and Jade Jagger. In the men's section, customers can play darts against "Gossip Girl" star Ed Westwick.
Henri Bendel: For $75, shoppers can have their own Red Carpet Moment by wearing one of five celebrity red-carpet looks by Marchesa and getting gussied up by the team at Frederic Fekkai. "The City" star Olivia Palmero will advise guests on their paparazzi poses before they are sent home with a memorable photo.
Erin Wasson will show off her Low Luv jewelry collection and famed astrologer Susan Miller will give 10-minute readings for $25 (with benefits going to charity).
Bloomingdale's: At the uptown flagship location, guests can decorate cookies with Tadashi Shoji, meet Lela Rose, Elie Tahari, Billy Reid, and John Varvatos, and receive tango lessons courtesy of Lancôme (who will have models Elettra Wiedemann and Arlenis Sosa on hand).
Cynthia Steffe, and Pour La Victoire designer David Giordano will hang out at the downtown location.
Lord & Taylor: "America's Next Top Model" photographer Nigel Barker will photograph any customer who makes a purchase of $100 or more, while Hilary Rhoda and Shoshanna Gruss will greet fans.
Dolce & Gabbana: Guest of honor Naomi Campbell will celebrate her 25 years in the business and sign limited-edition T-shirts featuring her image. Choreographer Laurie Ann Gibson will perform.
Balenciaga: Model/singer Karen Elson will perform songs off her new album, while the boutique displays the U.S. exhibition debut of new works by photographer Cindy Sherman.
Ralph Lauren: Vogue's Andre Leon Talley will host at the Soho location, while stylish singer Janelle Monae rocks out.
Rag & Bone and Philip Lim: The two shop neighbors are teaming up to host a Mercer Street party with a DJ, burgers, and shakes. Famed makeup artist Gucci Westman, the wife of Rag & Bone's David Neville, will give mini makeovers.
Giorgio Armani: Fashion icon Lauren Hutton shares stories with actress and writer Joan Juliet Buck.
Chanel: Customers at the uptown location can color-customize the iconic Chanel ballet flats alongside real ballerinas from the New York City Ballet, while downtown in Soho guests will receive complimentary manicures in the newest Chanel shade, Les Khakis de Chanel, designed exclusively for FNO.
Payless: Four of the company's guest designers -- Christian Siriano, Lela Rose, Patricia Field, and Isabel Toledo -- will meet customers. The shoe brand will also provide double-decker Gray Line buses to shuttle passengers around to FNO events.
Opening Ceremony: Sure to be one of the hottest parties of the night, the emporium of hip will stage a French flea market in the lobby of the Ace Hotel inspired by the iconic Les Puces de Saint-Ouen market in Paris. Designers like Alexander Wang, Proenza Schouler, Rodarte, and Joseph Altuzarra will man their own booths, as will famed macaroon makers Ladurée.
To see what the rest of your favorite shops and brands are up to on Fashion's Night Out -- even if you don't live in New York -- head over to fashionsnightout.com.
And beauty fiends should check out StyleList's guide to the best hair and makeup events of the evening.