Marc Malkin

Doane Gregory/20th Century Fox

Allison Janney may not have kids of her own, but she sure does the mommy thing really well.

Earlier this year, she stole every scene she was in as a hilariously rigid, Bible-thumping mom in Hairspray. And now, in the comedy-drama Juno, she’s the supportive stepmom of the title character, a pregnant high schooler played by Ellen Page.

“Those two are on completely different ends of the spectrum for mothers,” Janney said with a laugh. “I was just offered another mother [role], but I decided not to do it. I need to take a break from moms right now.”

But when she was making Juno, Page's prosthetic baby bump got her thinking. "There were all these different ones, but she wore the big, heavy one because it was more like the real weight," Janney said. "I wanted to try it on. I haven't been pregnant, so it would have been fun to try it."

Janney said she was hooked on Diablo Cody’s script for Juno by page two.

And when she saw the movie for the first time at the Toronto Film Festival, “I was just crying buckets and buckets,” the former West Wing star said. “I just wanted to go be by myself after I saw the movie, because it had such an emotional impact on me...It just really affected me.”

Audiences and critics seem to feel the same way. The Jason Reitman-directed movie, which costars Superbad’s Michael Cera as the baby daddy and J.K. Simmons as Juno’s father, is being touted as an awards-season favorite. It has already picked up four Independent Spirit Awards nominations.

“It’s how real people deal with problems,” Janney said. “A lot of times in these scripts it’s so overdramatized, like for an after-school special. But these are real people dealing with real problems. It’s messy. It’s not always black and white, and it’s complicated, but you get through it. It’s a great role model for families.”

Shirlaine Forrest/WireImage.com

Up next for Janney is a project with Dolly Parton. Janney will costar in the stage musical adaptation of 9 to 5 in the role originated by Lily Tomlin. Directed by two-time Tony winner Joe Mantello, the show costars Stephanie J. Block, Megan Hilty and Marc Kudisch and starts its pre-Broadway run Sept. 3, 2008, at L.A.’s Center Theater Group/Ahmanson Theater. Parton has written nearly 20 songs for the long-in-the-making show.

The cast and crew workshopped 9 to 5 last summer. “Dolly would come every day in her unbelievable outfits,” Janney said. “She’d come in and model for us.”

The country music legend would also arrive bearing gifts. “She’d come with peanut butter fudge or whoopie pies she made the night before,” Janney said. “And then she would sit there and write new lyrics during the course of the day. She would write lyrics on a paper plate. I would be trying to take the paper plates home with me, but she has people who grab those kinds of things to save them for her archives.”

Rehearsals don’t start until July, but Janney begins her voice lessons next week. “I was a little nervous,” Janney remembered about the start of the workshop. “I could sing, but I am not a Broadway singer. I can’t read music. But Dolly was like, ‘Allison, I can’t read music either. I’m not like these other girls, too. Me and you are very much alike.’ ”

For more on Juno and its Hollywood premiere earlier this week, click below for my Planet Gossip Now videoblog.