(FORTUNE Magazine) – If you don't have kids under 15, chances are you won't know what to make of the tidal wave of publicity about to be unleashed for Rugrats, the movie version of Nickelodeon's top-rated cartoon TV show. According to Marketing Evaluations/TvQ, 8-year-olds recognize Rugrats like Tommy and Angelica more readily than they do Bugs Bunny. But for the rest of us, Rugrats don't yet enjoy the buzz garnered by the foul-mouthed tykes of South Park or by Bart and Homer Simpson.

That's about to change. In conjunction with promotional partners like Burger King and Lincoln-Mercury, Nickelodeon's parent, Viacom, is launching a $100 million push to support the film, which will be released Nov. 20. Media companies always tout the "synergy" of their far-flung divisions, but this is one example that looks as if it's working. All of Viacom is helping get the word out about Nickelodeon's first animated film. (The network has made two live-action films, which were modestly successful.) Paramount Television's Entertainment Tonight is airing numerous segments promoting the show. Sister network VH1 will air a half-hour special on the film hosted by Lisa Loeb, a singer featured on the soundtrack. The special will then be replayed twice on Showtime--another of Viacom's cable networks. Showtime is even plugging the movie in the direct-mail promotions it sends out to lure viewers.

Viacom's hope: to ensure that the film version of Rugrats helps establish Nickelodeon as a major brand in kids moviemaking.

It's already a huge brand on television. For the past three years Nickelodeon has been the most watched network among kids ages 2 to 11, surpassing former champs ABC and Fox--pretty impressive considering the network reaches 27 million fewer homes than ABC. "Nickelodeon is the gold standard for reaching children," says Peter Chrisanthopoulos, president of broadcast and programming for Ogilvy & Mather, which buys ads for Mattell and Hershey. Adds Jack Irving, executive vice president at Saatchi & Saatchi: "If there's any advertiser looking to reach kids, Nickelodeon is the first place they look." This attitude has fattened Nickelodeon's cash flow: The network will generate $397 million this year, up 37% from 1997, according to Bear Stearns. "[Nickelodeon] is one of the major growth engines of Viacom," says CEO Sumner Redstone.

Still, encouraging outlying divisions to work together to support a successful franchise can be awfully risky. Consider a few recent examples: At Disney, broadcast network ABC ran prime-time specials to promote the parent's 101 Dalmatians, Hunchback of Notre Dame, and Flubber, scoring miserable ratings for each show. Time Warner's CNN Newsstand series, intended to broaden the strength of its magazines (including FORTUNE), kicked off with a story about Vietnam that both CNN and Time later retracted. And look at Twentieth Century Fox's summer film version of The X-Files, Fox's hugely successful TV show. The movie's modest profitability may have come at a big price. It failed to draw new viewers into the X-Files cult, and ratings for summer reruns of the show tanked 18% from 1997, indicating that even die-hard fans may have gotten their fill of all things Mulder and Scully.

If Viacom manages The Rugrats Movie as skillfully as it has the TV show, it should avoid those pitfalls. Rugrats isn't another fad like Mighty Morphin Power Rangers or Teenage Mutant Ninja Turtles. It's a carefully nurtured franchise that's still growing in its eighth year, a time when most TV shows wilt. Ratings rose 5% last year. Its 18 airings per week reach 23 million viewers, making it the most watched show among kids. The show has generated more than $1 billion for Viacom; that includes revenues from advertising, international sales, a live touring show, home videos, and licensing deals. (You can buy the characters on anything from kites to CD-ROMs.) The wealth is spread throughout the company: To cite just two examples, Paramount's home-video division distributes tapes of the cartoons, while Simon & Schuster publishes Rugrats books. (Viacom sold off the nonconsumer publishing part of S&S in May, but the Rugrats portion is still in-house.)

If Viacom can similarly insinuate the movie into its various divisions, Rugrats' success won't be measured at the box office alone. In an era of $200 million movie budgets, Rugrats is a comparatively safe bet--Viacom spent $25 million to make the film and is putting up another $25 million to promote it (the remaining $75 million comes from promotional partners). But check out all the potential revenue as Rugrats winds its way through Viacom. Combine the film's built-in audience with good buzz among industry insiders, and you've got a movie that could generate $100 million or more at box offices worldwide (Rugrats is also a big hit in England and Australia). This success could boost sales of Simon & Schuster's Rugrats books, of Rugrats toys and clothing, and of tickets to the live show that tours the U.S. Viacom could get a healthy sum by selling the TV broadcast rights for the movie. (NBC reportedly paid between $10 million and $15 million apiece for DreamWorks' animated pictures Antz and The Prince of Egypt.) Once Rugrats moves to video, it will generate millions in sales and rentals for Paramount's home-video division and for Blockbuster, Viacom's video chain. Finally, the movie will end up on Nickelodeon, where it'll be played ad infinitum, bringing in perhaps $30,000 to $40,000 for each 30-second commercial spot, as the show currently does.

How will this affect Viacom's bottom line? It takes a blockbuster like 1994's Forrest Gump, which also traveled through Viacom's empire, to bolster a company's stock, says Tom Wolzien, a top media analyst at Sanford C. Bernstein. (Wolzien sees Viacom, now at $62 a share, reaching $75 in the next 12 to 15 months.) "[Rugrats] probably doesn't boost the stock price, but you have the potential to build a franchise there," he says.

And that, finally, is what Viacom is banking on. "Low-cost motion pictures from MTV and Nickelodeon have a great chance of success, and serve to offset the general cost of production and marketing in Hollywood," says CEO Redstone. Redstone says he'd like Nickelodeon to pump out four movies per year, including one large, heavily hyped animated film. To meet this goal, Nickelodeon has numerous projects in development, including one based on the burgeoning hit TV show Hey Arnold! and another on Prometheus and Bob, a cartoon short about an alien and a prehistoric man. "Each extension of Nickelodeon strengthens the brand," says Redstone. "The success of Rugrats we feel assured about." Just how sure? The sequel is already in the works.