Are we going to see the characters move from Fifties styles to more Sixties-centric looks?
This season takes place in 1963, so we're still in classic Americana design, but we'll be seeing new shapes, for sure. I'm incorporating more of an A-Line silhouette.

Shorter hemlines?
They’re basically the same. The mini hasn't been invented yet!

What's the biggest change?
Betty. She's pregnant. In Season One, I designed all the padding for Peggy and I'm doing that for Betty now. But it's a totally different design. Peggy was supposed to be a fat-disguised pregnancy but with Betty, we know she's pregnant.

How about Joan?
She'll always have a pinched waist. She's someone who'll always want to show off her figure.

And Peggy?
We'll be seeing a few more suits for her, now that she's really immersed in a man's world. But I always like to have her as a modest character.

Do the actors and actresses make suggestions?
Not too much. But Elizabeth Moss [who plays Peggy Olson] is like, “Janie, please—no more mustard!” I tell her it's so the period and so her character. Mustard is good.

For its 40th anniversary, Sesame Street is doing a parody of Mad Men. Are you helping out with the costumes?
Oh, my God. That's fantastic. I didn't even know about that. I hope they call me.

See our interview with Mad Men star Jon Hamm from the July 2008 issue.

Photos: Jones and Moss: Carin Baer/AMC. Hendricks: Frank Ockenfels/AMC