The Simpsons executive producer Al Jean

After 20 years and nearly 450 episodes, The Simpsons received a surprising distinction: an endorsement from the Vatican.

"I called my father — whose been going to Catholic Mass for 70 years — and I said, 'So it turns out I've been doing God's work all this time,'" laughs longtime executive producer Al Jean. (The official Vatican newspaper praised the show last month for its "realistic and intelligent writing.")

Even without the Roman Catholic Church's approval, the series has thrived. Playing in more than 90 countries, the longest-running prime-time scripted series will simultaneously celebrate its 20th anniversary and 450th episode Sunday. The Simpsons 20th Anniversary Special: In 3D! On Ice!, airing Sunday at 8:30/7:30c, will look back at both the show's humble origins and worldwide impact.

TVGuide.com talked with Jean — the series' current showrunner and a writer since Season 1 — about the show's anniversary, his favorite characters and guest stars.

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TVGuide.com: How does it feel to be celebrating the show's 20th anniversary?
Al Jean: I can't believe it. Everything I do with the show is more surreal than the last ... It doesn't seem very long ago at all that I was just starting. It's like a waking dream, like where you have these crazy things that are really cool happen again and again, with the guest stars we've had and the countries we're seen in ... I'm still driving the same car by the way [laughs].

TVGuide.com: An entire generation has grown up with the show.
Jean: It's bizarre. I have a daughter who's 19 ... We are seeing the generation that has been raised by The Simpsons. I don't know if that's good or bad [laughs].

TVGuide.com: Some of the very early episodes you and [frequent co-writer] Mike Reiss wrote introduced important supporting characters Apu, Ralph Wiggum and many others. Which supporting characters were you the most involved in creating?
Jean: I would say Ralph Wiggum, Bleeding Gums Murphy and Troy McClure would be three. It's always been such a team effort and so many amazing people involved with it, every character is a compilation of all the writers and the actors and the animators. It's a shared experience.  

TVGuide.com: What was your inspiration for those characters and the show as a whole?
Jean: I think that Ralph, even his name, was influenced by Ralph Kramden [of The Honeymooners]. He's certainly somebody who we thought was just the funniest TV character ever. Influences that the show has had, I would say Second City TV was a huge one ... Classic '70s sitcoms like The Mary Tyler Moore Show [influenced us because] this was the first attempt to write an animated show in that style.

TVGuide.com: You and Reiss also have written some of the early emotional episodes of The Simpsons, such as when Lisa is depressed and when Bleeding Gums dies. Was it hard to dive into that aspect of the show?
Jean: The reason why we choose that path a little more than others is because we had just come off The Tonight Show and The Garry Shandling Show. We were regarded as a little sketchy, in the way people like to pigeonhole writers. When we were working for [James L.] Brooks, we thought let's go for these really emotional but funny shows that Jim is well known for.

TVGuide.com: One of the episodes you and Reiss wrote was "Stark Raving Dad" with Michael Jackson. After he died this past year, did the significance of that episode and his talent on the show really set in?
Jean: It was one of the many amazing things that happened to me while working on the show. He had said to Jim Brooks, 'I want to be on the show and I want to write a No. 1 song for Bart.' And he did and he did, it was No. 1.[Jackson co-wrote — although uncredited — the song "Do the Bartman," which reached No. 1 in the United Kingdom, Ireland and Australia.] He did come to the table reads and read the script but when it came to the singing, he wanted a sound-alike to do the recording and we never really understood why. I did hear him sing and of course he was great. It was one of the coolest things I've been involved with.

TVGuide.com: Over the years, it must get very hard to find new ideas and new territory that hasn't been covered on the show yet. How do the writers avoid that after 20 years and 450 episodes?
Jean: It's hard, there's no doubt — 450 episodes and we often do two story lines per episode so that's about 900 plot lines. I'm familiar with every episode and I've seen all of them, so I think, we can send them to an amusement park again but it has to be different ... If you're exploring emotions, obviously we've done different shows that deal with a marriage but marriages have many different aspects to them. Just because you've done one or two or 450, doesn't mean that you can't explore new territory. As long as people have problems and families have issues, I think we'll have shows.

TVGuide.com: The show has gotten a lot of flak for possibly not being as good as it was in the early years. You were heavily involved in the early seasons as well as the most recent years so why do you think that is? What do you say to those critics?
Jean: There's different responses. One would be: maybe we've declined but at a slower rate than the rest of the world. It's very hard to be objective because I've been hearing the same thing since Season 2 ... by objective standards, we're doing really well.

TVGuide.com: Looking back over the entire series, do you have a favorite guest star or character or episode?
Jean: My favorite guest star might be Kelsey Grammer [Sideshow Bob] and it's a really tough contest because there are so many great ones. His voice gives you so much ... Favorite character, I love writing for Lisa. And favorite episode is impossible.

TVGuide.com: Is there any particular reason you like writing for Lisa?
Jean: Because I was never cool like Bart, so that was the character I gravitated towards and Yeardley [Smith, the voice of Lisa] is great. 

TVGuide.com: When and how do you think The Simpsons will end?
Jean
: I don't think the end is imminent ... There have been a lot of great endings but we've done them all. Like the "Behind the Laughter" episode. "Eternal Moonshine of the Simpson Mind" would have been a good one. "Lisa' First Word," when Maggie spoke, would have been a good one. One thing I learned in television is don't save it; if you got something good, air it. I have an idea for the last episode but I don't want to say it.