Creator Theresa Rebeck, songwriters Marc Shaiman and Scott Wittman tell THR how the series has changed since its inception at Showtime, comparisons to the Fox hit and just who the series is made for.

A Broadway pedigree. Nine award-winning executive producers, including Steven Spielberg. A budget pegged at $3.5 million per episode. And the hopes of an entire broadcast network riding on it. Much has already been said about NBC's Smash leading up to its Monday premiere.

Starring Debra Messing and Christian Borle as playwrights prepping a Broadway musical about Marilyn Monroe, Smash takes an insider's look at the theater world -- including the battle that ensues when a newcomer (American Idol's Katharine McPhee) goes head-to-head with a stage vet (Wicked's Megan Hilty) for the lead role.

The Hollywood Reporter sat down with creator Theresa Rebeck, songwriters Marc Shaiman and Scott Wittman last month to discuss the making of a drama series about the making of a Broadway play, being dubbed "Glee for adults" and just how they approached creating the unique series. Here are five things to know about the series.

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1. Original songs: Tony-winning Hairspray duo Marc Shaiman and Scott Wittman penned between 15 and 17 original songs for Smash, spending countless hours researching Marilyn Monroe. The duo drew from more than 80 books about the icon and approached the process as if they were actually writing a musical about Monroe. "We start free associating words that come from our point of view," Shaiman says. "We don't ever start writing a song until Scott has the idea of what that song needs to accomplish."

Among the original tracks, lots of Joe DiMaggio-Marilyn songs; one about Marilyn's famous The Seven Year Itch and a song for Monroe during her "bad" phase, which was the biggest "mind f---" of all the songs, Shaiman says. "To be in a theater, shooting a musical number for a TV show, the musical number is a number for a Broadway musical but the number itself is taking place on a soundstage," he says.

2. Broadway bound? Could the Marilyn musical at the center of Smash head to Broadway? Shaiman, Wittman and Rebeck aren't in a hurry to answer that. "We would have to revamp the material if that ever were to become a real musical," Shaiman says, noting that NBC Entertainment topper Robert Greenblatt said from the start that all the music featured on the series would have to naturally fit and make sense in an actual musical. Adds Rebeck: "I think that people are thinking about it though, but for now my focus is building a great show. Ask me that question again in a year and see what I say."

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3. The Glee affect: Dubbed "Glee for adults," the executive producers credit the Fox series for paving the way for Smash. "Actually, it's a perfect description," Shaiman says. "To say it's Glee for grownups is not any kind of a dig at Glee; it just means out characters are older." The musical duo, who worked with Glee's Matthew Morrison when he starred as Hairspray's Link on Broadway, are even open to welcoming him -- and other Glee cast -- to Smash. "[Morrison] just texted us and said, 'Could I direct Smash?' I thin that would be a great idea, someone from Glee directing one of our episodes," Shaiman says. "The world is big enough for both these shows. No one says, 'Oh, there's enough … you can't have another cop procedural on TV.' "

4. Who is Smash made for? Series creator Rebeck -- an accomplished TV writer (NYPD Blue), playwright The Understudy) and author (Three Girls and Their Brother) -- says she had some trepidation about doing Marilyn the musical first came up. Ultimately, she says, it was her approach to Smash as a TV series that pushed the idea forward. "There were a lot of people who were nervous about the idea," she says. "I finally said, 'I don't know if I could write a great musical about Marilyn Monroe, but I know I could write a great television show about people trying to write a musical about Marilyn Monroe."

Shaiman and Wittman, meanwhile, say they approach the songwriting as if they were writing for their type of audience. "The characters portrayed by Debra Messing and Christian Borle are kind of our counterparts in the show," Wittman says. "We try to write something that would be their vocabulary."

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5. Changes for broadcast: Smash was originally developed at Showtime and when Robert Greenblatt departed premium cable network to head NBC's entertainment unit, he brought the project -- then a 70-page script -- with him.Since the network -- and subsequent audience shift -- Rebeck says writers "lopped off" about 20 pages of the script and break the story sooner. "There was more language and nudity and some slightly darker behavior patterns, although we were kind of building to that," she says. Much of the material that was taken out of the pilot Rebeck says went into subsequent episodes. "The pilot is, in ways, extended through Episodes 2 and 3."

Smash premieres Monday at 10 p.m. on NBC. Will you watch?

Email: Lesley.Goldberg@thr.com; Twitter: @Snoodit