Screenwriter and former Vancouver resident Seth Rogen scores the lead in Knocked Up.

LOS ANGELES–If the Los Angeles Times is to be believed, the next great film comedy star will be an overweight, somewhat homely ex-Vancouverite. The paper recently polled L.A.–area teenagers after showing them trailers for upcoming summer releases. Although the trailers for expensive film sequels like Spider-Man 3 and Pirates of the Caribbean: At World's End were popular with the teens, the top two films on the list were comedies either written by or starring 25-year-old Point Grey Secondary School dropout Seth Rogen. On top of the list was the August release Superbad , a film that costars Rogen and was written by him and Evan Goldberg when they were still attending the Kerrisdale high school. Finishing second was Knocked Up , which stars Rogen as an unemployed L.A.–based ex-Vancouverite who gets a beautiful television host pregnant during a one-night stand. The movie opens Friday (June 1).

Rogen was just 13 when he made his professional standup-comedy debut at a Gastown club. ("It was a lesbian bar," he says in an L.A. hotel room. "I thought it was ladies' night. I didn't really get what was happening.") At 16, he sent off an audition tape to a television producer named Judd Apatow, who was looking for actors for a new TV series called Freaks and Geeks . Apatow liked the tape, and Rogen and his parents moved to Los Angeles. Apatow–who went on to cast Rogen in another series, Undeclared , directed him in Knocked Up , and produced Superbad –says that his decision to take a chance on an unknown kid worked out well for everyone.

"Someone gave me a tape of actors doing generic scenes for Freaks and Geeks , and he was funny and he seemed real, and I was looking for kids that seemed authentic. There was no part for him in the show, and he came down and he brought his parents and I realized that I had altered his entire life. His whole family had moved to America because we found him humorous! But he seemed to have been born as a fully formed comedic personality, so I made him a writer on Undeclared [a series about first-year university students] even though he hadn't gone to college. Of course, the reason he hadn't gone to college was because I had ruined his life and ended his education."

When the series was cancelled in 2002, Rogen could find only supporting roles in films and television shows. However, he kept writing, and he and Goldberg eventually won Emmys for their work on Da Ali G Show . Then, in 2005, Apatow cast Rogen as a friend of the lead character, played by Steve Carell, in The 40 Year Old Virgin . Two years later, Apatow has him playing the lead in Knocked Up and has surrounded him with Rogen's real-life L.A. friends.

Rogen says that playing a lead opposite Grey's Anatomy 's attractive Katherine Heigl would have been more intimidating if Apatow hadn't allowed him to work with his real friends and to improvise the dialogue.

"The [sex] scenes [with Heigl] were a little nerve-racking," he says. "If I was 18 years old, that would have been as far as I had ever been with a girl, because you are essentially dry-humping with someone you don't know very well. I was just afraid that I was going to sweat on her. Luckily, they are comedic sex scenes, so that kind of helped. It's not like I am supposed to be acting sexy. And I got to act with my friends because we had hoped that those dynamics would show on film and that you could see that we were real friends.

"We felt the best way to get that across to the audience was to improvise. We had to be loose and to let the dynamics play out, so we improvised heavily. We would shoot the scene once, and then we would just go off [script]. Harold Ramis [who plays Rogen's character's father] said that when they [Ramis, Dan Aykroyd, and Bill Murray] did Ghostbusters they would refer to the script as 'the worst-case scenario'. I get that. It's what you have if you can't find anything else."

When he left Vancouver for Los Angeles, Rogen was just a few months away from entering Grade 12. He was supposed to finish high school through correspondence, but he got busy shooting Freaks and Geeks and admits he "never got around to it". However, he says he has no regrets. "Not yet, but we will see. So far it hasn't come up. Right now it is completely irrelevant because I have found the one job you need no education at all to do."

That job will probably lead to his becoming one of the highest-profile writer-actors in Hollywood if Knocked Up , Superbad , and next year's The Pineapple Express , which he also cowrote and stars in, are hits. He says that he is particularly proud of Superbad , the movie that he wrote with Goldberg when they were just 14. There have been a lot of high-school films, he says, but neither he nor Goldberg felt that there had been anything that mirrored their own experiences. The film takes place over the course of one night, with Knocked Up 's Jonah Hill playing "Seth" and Arrested Development 's Michael Cera playing "Evan". Rogen plays a local cop charged with keeping the underage kids from buying alcohol.

"We thought it was all pretty funny in a way that we hadn't seen in movies before. I don't know if it [Point Grey] was any funnier than any other high school. We just knew that our experience wasn't being represented in movies. The way we spoke wasn't being shown, and what we did on the weekends wasn't being shown. When we first started writing it at 14, we didn't expect it to get made. We just did it to amuse ourselves. We just thought, 'What if we wrote a high-school movie when we are still in high school? What would that be like?' So it came from us wanting to write characters who were like us, which is why we gave them our names. We had to change the names of the teachers because we couldn't legally clear them, but we got clearance for everyone else, so that pretty much all the names in the movie are names of people we went to high school with. Anyone who is referenced has the name of the real person we knew."

Rogen approached the script of Superbad from the point of view that it was time for a movie that did away with high-school stereotypes, and he and Apatow appear to have come to Knocked Up with a similar attitude. He says that they didn't want to make a traditional movie about a young slacker.

"We wanted to show that almost any guy is redeemable," he says. "If you haven't done something really terrible, there should be some kind of redemption. I think this film has a simple message: try to be a good guy or girl. That is all you need for your premise. You can have the characters saying all the despicable and filthy things you want and have them doing stupid things, but if you can get across the point that the character is trying to be a good person throughout it all, then people will care about them and be interested in the outcome. It's simple, but emotionally speaking it is true to my experience with people. You know that everyone has their shortcomings, but as long as you see that they are generally trying to do well by others they are redeemable."