Leslie Morgenstein, Alloy Entertainment CEO: We had taken a couple of cracks at developing the Gossip Girl books elsewhere. There was a script at Fox, and then we took a shot at a feature. The rights came back to us a couple months before the CW merger. We spent some time talking about how both Fox and The WB really broke through with sexy teen soaps: 90210 on Fox, Dawson's Creek on The WB. It seemed to us like Gossip Girl had the potential to be that for The CW. We talked to our studio partners, who got the books to [then-CW entertainment chief] Dawn Ostroff.

Peter Roth, Warner Bros. TV President: In 2007, The CW was in its infancy and looking for a signature series. These books spoke magnificently well to the possibilities of the network. As far as a producing team, Josh [Schwartz] and Stephanie [Savage] were the only choice. Coming off of The O.C., I've always thought of Josh as the pied piper of this generation.

Dawn Ostroff, former CW Entertainment Chief: We knew we wanted to go after 18- to 34-year-old women and do scripted content that was going to be bold. Gossip Girl fit so many of the characteristics that we were looking for.

Josh Schwartz, Co-Creator: Just as The O.C. was ending, Alloy sent me the first Gossip Girl book. I thought it was interesting, so I sent it to Stephanie. I said, "If you like this, we should do it."

Rick Haskins, the CW Executive vp Marketing and Digital Programs: It was fresh and fun and really captured how people talk about each other. It spoke for the first time to a digital audience in a very honest way. The premise of Gossip Girl -- a blogger with her own reporting website -- was very much a precursor to the reign of Facebook.

Stephanie Savage, co-creator: We pitched the network our take of how we would do this show.

Schwartz: It was a super-elaborate pitch of this New York fairy tale -- very archetypal characters: a princess, a knight in shining armor. I remember when it was all over, Dawn said: "You guys know we already bought this, right? You didn't really need to do that much."

Ostroff: It was very easy to see their vision. There were so few notes. There's just no way we wouldn't have made this. When we saw their pitch, we thought: "This is it! This is everything we want!"

Schwartz: When we first started casting, we read a lot of blogs that said, "You need to cast Blake Lively as Serena van der Woodsen." We were like, "Isn't that the girl from the [Sisterhood of the] Traveling Pants movie?" After we convinced her to do television, the network was concerned that she was "too California." So we dressed her up in boarding school attire -- clothes out of Stephanie's closet -- and straightened her hair to prove that she could look New York.

STORY: 'Gossip Girl' Producers Tout 100th Episode

Savage: I had worked with Penn Badgley [on WB's The Mountain] and had told him several times to stop doing WB pilots. Then I had to go back and say, "OK, one more!"

Schwartz: Ed Westwick came in and blew us away. He originally read for Nate, but Stephanie and I looked at each other and wrote, "Chuck?" on a piece of paper. Once we cast him, he had to figure out his green card. We got several calls that he actually wasn't going to get it in time.

Savage: The network was like: "You have to have a backup choice. We can't delay production. It would cost hundreds of thousands of dollars."

Schwartz: But we refused to make the pilot if Ed wasn't Chuck Bass. Chace Crawford was very new and probably read 30 times.

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Chace Crawford, actor: I went back and forth to countless auditions because [CBS president and CEO] Les Moonves needed to sign off on me. They stuck me in this empty room with a hundred vacant chairs around a conference table. I sat down and this girl swiveled around in her chair, and it was Leighton [Meester].

Schwartz: Leighton was a blonde when she came in to read, but Blake was the blonde, so we asked her to color her hair. A risky move on her part in the middle of pilot season, but she did a sink-rinse dye job to audition as a brunette.

Leighton Meester, actress: I started auditioning back in December 2006. The process was really long. At the time, I wanted to move to New York, but I didn't have a reason or any money. So when my agent sent me the Gossip Girl script, I thought Blair was perfect for me. Originally the script had my character suffering from an eating disorder, but they ended up taking it out.

Schwartz: Taylor Momsen [who played Jenny Humphrey and has since left the series] was an innocent 13-year-old when she came in. She played us the sweetest, poppiest Gwen Stefani music. (Laughs.) As for Matthew Settle and Kelly Rutherford, we really had to fight to get more money to pay for them. It was important to have adults to anchor the show.

Haskins: The hardest thing about launching a new show is that people don't know the characters yet. You have to do an overall concept sell. We launched with a tagline: "You're nobody until you're talked about."

Schwartz: When it premiered in September, it got a lot of buzz, but we didn't necessarily come out of the gate and pop a number.

Ostroff: It was incredibly frustrating. Nielsen doesn't have a great grasp on measuring younger viewers. You couldn't go anywhere in the country without finding people obsessed with the show. Where Gossip Girl ranked No. 100 on the Nielsen list, it was No. 13 when you looked at the power-content ratings -- a combination of Nielsen ratings, traffic online and buzz.

Schwartz: Everyone told us these shows take time.

Meester: When we first started filming, people would walk by and ask, "What are you filming?" Once we aired, the whole mania started.

Crawford: We were shooting on the Upper East Side one afternoon and must have been outside three all-girl schools. Within an hour, 10 girls multiplied to 300. I mean, we weren't the Beatles. Ed and I were crossing Park Avenue and had a ring of girls around us. We got stuck on the median and our make-up people had to fight them off. They were getting their hair pulled and had to throw elbows to get us through.

Ostroff: I'll never forget, I had someone come in from China to talk to us because the series was the No. 1 downloaded show in China -- obviously not legally, but it had created a huge phenomenon.

Schwartz: Then the writers strike hit. It was devastating and scary. Initially, we wondered whether the show would ever come back.

Meester: I thought every episode was going to be the last one.

Schwartz: We ended up being one of the few shows that came back that year with new episodes, but because we had been off the air for so long, The CW had to relaunch the show.

Haskins: We used an outside research company and went to different markets to sit in living rooms with viewers: Chicago, Atlanta, Denver, Dallas and New York. We began to see how viewers were talking about the show. They would text each other about it, even if they were sitting on the same couch. That really was our "Aha!" moment. We realized we could flip our marketing and talk about this show the way they talked about it.

OMFG

Haskins: When I saw the "OMFG" ads, I knew that was it, but then I had to sell it internally. A lot of people didn't know what "OMFG" meant, so I had them call in assistants to get their reaction. The assistants would either smile or gasp. Once that happened, I had 100 percent support.

Ostroff: As controversial as it may have been, the campaign set the tone for the network and the brand.

Haskins: That's when Gossip Girl went from 60 to 120 miles per hour. We planted a very strong flag in the marketplace, and to this day we're known as the "OMFG network."

Savage: We loved it. It was using the language of the show to promote the show. It felt smart and had attitude.

Haskins: A lot of companies would not put "OMFG" on billboards or [run it on] certain cable stations, so we created two alternatives: for some an emoticon and for others we changed "OMFG" to "OMG."

Crawford: I remember Jay Leno doing a bit where he asked an old grandma what "OMFG" meant. (Laughs.) Oh, and being shirtless on a poster with some girl.

Haskins: The message got out loud and clear. We had a lot of negative things said about it. For phase two, we took negatives and turned them around. We used the "Mind-blowingly inappropriate" and "Every parent's nightmare" quotes to sell the show. The Parents Television Council gave me the nickname the "snake in the grass at The CW."

Lisa Gregorian, Warner Bros. TV Chief Marketing Officer: It was provocative, but we didn't want to do it just for the sake of getting attention. The show had to back it up.

Haskins: The next year we did the "WTF" campaign. We'd show provocative scenes that were coming, and then we'd cut to a card that said, "WTF?" before panning out and seeing "Watch This Fall." We were in a groove; we really understood what the brand was and, more importantly, we understood how to talk to our viewers.

Savage: Like the campaign, the show is edgy, but we have a great relationship with the network's standards-and-practices people. Whenever we do anything where we feel like we might be controversial, we have a lot of conversations. When we did our threesome episode in season three, we definitely caught some flack.

Meester: We're not whitewashing on this show. We're talking about issues people hold back on: drinking, drug use, sex. We're not pretending it's glamorous; we're just portraying something teenagers do.

Morgenstein: I live on the Upper East Side, and the reactions shifted from moms of young teen girls being upset about the show to those same moms being fans of the show and wanting set visits.

BREAKING OUT

Savage: All of a sudden, people wanted to do cameos. During Lily and Bart's wedding episode, I was working with [baker] Sylvia Weinstock on the cake and thought: "Sylvia is a New York celebrity. She should come to the wedding." [Socialite] Tinsley Mortimer came to our white party, then Michael Kors, Tim Gunn and Vera Wang.

Ostroff: It started a fashion craze. During the second season, there was a front-page article in The New York Times about Gossip Girl's fashion and how stores like Bloomingdale's couldn't keep the show's clothes on shelves. People watch the show the way they read a magazine: They want to know where to get the clothes, where to get the music and where to go in New York.

Schwartz: New York really embraced us. When you're first shooting, nobody wants you there. All of a sudden, bars and restaurants were opening their doors. Our New York magazine cover was a big deal because it was a larger New York cultural magazine. The pinnacle, though, was Rolling Stone. It's really very gratifying because you believe in these actors early, but there's no evidence to suggest you're correct yet.

Meester: You always want to grow and change, and the show has allowed me time off to pursue other projects and parts of the business. The biggest highlight for me is the 100th episode. It was a dream because my character wears this gorgeous Vera Wang dress. And because it took eight days to film, I wore my wedding gown way more than a typical bride would.

BIDDING FAREWELL

Mark Pedowitz, CW President: This is the first CW show to hit 100 episodes, and we have great pride in it. We hope that it lasts for a long, long time. Time will tell how things go.

Schwartz: We're very proud of the 100th episode, but my favorite scene has to be Chuck and Blair's first moment in the back of the limo [during season one]. There's also a shot of Dan kissing Serena on a cobblestone street in the Meatpacking District -- it's moments like that when you say, "This is the show."

Roth: This was defining, much the same way CSI has been defining for CBS and Lost and Desperate Housewives were defining for ABC.

Gregorian: And it's resonated worldwide. It's in 197 territories and No. 1 with young adults and women on the channels they are on in Australia, New Zealand, France, Germany, Finland, Greece, Romania, Sweden and the U.K.

Schwartz: You hope that these shows can serve as time capsules. Hopefully this one will be remembered for the characters, how we were ruled by gossip and technology in a way that feels true. And hopefully we're remembered for capturing New York and what it was to be young there.

Savage: We have no plans to wrap things up this season. The actors' contracts expire at the end of next season, so that feels like probably an organic ending point.

Roth: I certainly hope we get at least one more season. We're contracted for another one. The show has had an extraordinary impact on all of us, and I'd be thrilled to be able to appropriately say farewell after six remarkable seasons.

♦♦♦♦♦

MEET THE PARENTS: On the eve of Gossip Girls' 100th episode, here are the key strategists behind the CW series that shaped and defined the 6-year-old, femme-focused network.
Dawn Ostroff, Former CW Entertainment Chief: The Gossip Girl cheerleader greenlighted the series shortly after launching The CW network in 2006.
Peter Roth, Warner Bros. Television President: As a top executive at The CW's co-parent, Roth has played an instrumental role in the series' success.
Josh Schwartz, Co-Creator: After making his mark as one of TV's youngest showrunners on Fox's The O.C., he was the network's first choice to develop the young-skewing series.
Stephanie Savage, Co-Creator: Together with Schwartz, Savage launched production company Fake Empire, which is developing The Carrie Diaries for The CW.
Leslie Morgenstein, Executive Producer: The Alloy Entertainment chief executive has overseen the young adult books on which the series is based.
Joshua Safran, Executive Producer: The onetime screenplay scribe has penned 18 episodes for the teen soap series, including the 100th episode: "Father and the Bride."