Judd Apatow makes it a family affair in 'This is 40'

A: "Sometimes I think, could someone else play this part? Am I doing this with Leslie because it's Leslie? I'll try to run the names - who would I have cast if it wasn't Leslie? And I can't think of anybody. There's zero people on that list who act that well, are that emotionally vulnerable, who could play comedy and drama simultaneously in the same scene, who go that deep. So that's the appeal for me: knowing someone that intimately who's so amazing at what she does, and then makes a gigantic writing contribution."

Q: What kind of writing contribution?

A: "With these movies, I don't write them and hand them to Leslie. They're written with her as my partner. I'm telling her the idea before I start writing and she'll say, you should talk about how good it feels when strangers hit on you, or you could do a scene based on that time the hockey team hit on me and my friends. That's the kind of collaboration that you can't get from someone you're not intimate with."

Q: What makes the two of you click on that level?

A: "Leslie comes at this as an actress. Being around her, and what interests her, has drawn me towards something that's more truthful and goes deeper. Her wanting to put herself out there completely makes me want to put myself out there completely."

Q: Will we see more of Debbie and Pete and their kids?

A: "I like the idea of it. If you said to me that 40 years from now there were five movies that track the arc of their lives, that would be the greatest thing ever. So I don't know if we'll do it, but I'm not closed to it."