As Bart Simpson skips into his 18th season of TV mischief tonight, fans will be glad to know that creator Matt Groening sees no end in sight for the wayward lad or "The Simpsons."

Groening's reasoning is sound: The show is fun to make, fun to watch, just earned its 23rd Emmy and is finally jumping to the big screen with a summer 2007 movie about Bart and the rest of Springfield's first family.

"My attitude at this point is, as long as the people who work on the show are having a good time, let's keep doing it," he said. "We've always tried to entertain ourselves and figured that the outside world would be entertained if we were making ourselves laugh."

The key is to keep surprising the audience. Groening acknowledged that's become tougher, because the show has "covered a lot of territory" through the years. It has, in fact, brilliantly lampooned nearly every aspect of American life and culture.

"But there's a really good-natured spirit of competitiveness among the youngest writers on the staff, who basically grew up watching the show and have a great memory for everything that's gone before," he said.

They also don't want to be the ones who disappoint the nation, not to mention the world. The series is seen in more than 70 countries, which along with scads of "Simpsons"-based merchandise has made it a reported billion-dollar cartoon cash cow for Fox parent News Corp.

"The people currently on staff are determined not to be the staff that caused the show to crash and burn. But also to try to top ourselves," Groening said.

"The Simpsons" has been renewed by Fox through its 19th year. The ensemble voice cast includes Nancy Cartwright as Bart, Dan Castellaneta as dad Homer, Julie Kavner as mom Marge, Yeardley Smith as sister Lisa, Harry Shearer as boss man Mr. Burns and Hank Azaria as police Chief Wiggum. (Azaria and several others in the cast perform multiple voices.)

Last month, it won its ninth Emmy for best animated series and has received best voiceover performance and other honors. Groening called the latest award "a shot in the arm. ... I thought people might be jaded but, no, they weren't."

The program is known for its stellar guest stars and promises not to disappoint this season. In an episode in which Lisa helps Moe the bartender become a poet, she encounters Gore Vidal and Tom Wolfe, voiced by the literary giants themselves.

"They don't usually do cartoons. You don't see them on 'SpongeBob,' " Groening noted, slyly.

Tonight's season opener revolves around Homer's brush with mob life and includes Joe Mantegna as Springfield's big boss, Fat Tony, and Michael Imperioli and Joe Pantoliano of "The Sopranos."

In a Sept. 17 episode with the White Stripes rock band, Bart is injured by a tiger that Lisa rescued and organizes a benefit concert to help pay for an operation on his drumming arm.

The landmark 400th half-hour, due to air next May, is a spoof of Fox's "24" that's titled "24 Minutes" and features the drama's Kiefer Sutherland and Mary Lynn Rajskub as their characters.

"Fox is very happy about this for some reason," said Groening, who at times has clashed with his corporate bosses about stories that carry more potential for controversy than network promotion.

Groening's schedule is especially full these days. Besides his work on "The Simpsons," he and partner David Cohen are bringing one-time Fox series "Futurama" back to TV with new episodes on Comedy Central beginning in 2008.

"My day started at 7 a.m." Groening said Thursday. "It's crazy. We just run from one room to another. ... People ask, 'Why did you wait so long to do a movie?' and now I have a really good answer. Because there's only 24 hours in a day and you have to sleep sometime."

The movie's timing was a well-kept secret that was sprung on the world when a trailer appeared in theaters last April. The plot remains under wraps although a rough-form snippet was shown last month at Comic-Con, the comic book convention, and Web speculation has it that a nuclear accident isolates Springfield.

Groening knows firsthand that "Simpsons" buffs are beyond ready for the film.

"It's really annoying coming on the (studio) lot everyday and having the security guard say, '214 days!' He's such a fan he can't wait for the movie," Groening said. "I don't come in that gate."

But he admits to his own eagerness.

"We've shown episodes of 'The Simpsons' to audiences at colleges, various conventions, and it's so much fun, such a different experience to see it with an appreciative audience," he said. "Part of my motivation for doing the movie is I just want to hear a theater full of people laughing at the cartoon rather than being at home in the dingy rumpus room."