Growing up in Montana in the shadow of Glacier National Park, Jenn Rogien -- who calls herself a true "Rocky Mountain girl" -- could never have been prepared for the Brooklyn hipster aesthetic she's helped carve out on HBO's hit series "Girls." In fact, she never could have predicted she'd become a costume designer.

Ms. Rogien headed east after high school, accepted into Yale as a chemical engineering major. She had always been convinced she'd be well suited for the sciences. There was an underlying passion she had for theatre, however -- she often sneaked off to the set of the latest production when she should have been doing her homework -- and Ms. Rogien fell in love with the environment at the Yale drama department. They hired professional costume designers and students to serve as assistant designers, which gave her the first glimpse of costume design as a full-time career. Out of school, she got a job at Saks Fifth Avenue, which gave her the basis she needed to study further at Parsons School of Design before breaking into the TV world.

She chatted with us about what it's been like working on "Girls" with Lena Dunham, Allison Williams and the other actors, and gave us a taste of what to expect from the costumes on the new show she's working on, the Netflix original series "Orange is the New Black."

Ad Age: You are one among an elite group of costume designers who have really broken out and begun to create a brand for yourself. How does one get into costume design for TV, and what's the appetite for this field right now -- is it healthy?

Jenn Rogien: I think it's becoming more recognized and there are more and more people interested in getting in costume design. There's so much interest in the show and inquiries I'm seeing via my personal website. There's a lot more interest in what people are wearing in general and watching what Kate Middleton is wearing or what Kim Kardashian is wearing, and, what your favorite character is wearing on your favorite show. It's different than fashion design and editorial styling -- and I think it's great for there to be another option out there.

Ad Age: You've worked on movies and on other TV shows like "The Good Wife" and "Lipstick Jungle." How's the "Girls" experience been different?

Ms. Rogien: In some ways it's a lot the same. It's definitely costume design -- starting from the script, getting the characters off the page, working with the actors and collaborating with the directors. One of the ways it's been very different is that the show has its own rules and I mean that in the best possible way. One of those rules is that not everyone has to look great on TV, which is a big paradigm shift.

One of the reasons people have loved TV is that everyone does look good.... Audiences have looked to leading ladies to look great and have great clothes and hair. But "Girls" has a very strong current of realism that makes it both challenging and liberating.

To shake off a little bit of the "Good Wife"-fairy dust did take me a minute to gear-down and realize that it was okay to be looser. And that part of the way to reflect where the "Girls" characters are in their lives and reflect the decisions they are making and experiences they are having is to loosen the wardrobe.

Ad Age: Do you see any brand integration possibilities -- like, for example, what happened with "Mad Men" and Banana Republic creating a line of clothing based around the way some characters dress? If so, what brands would you think would be appropriate fits with the show?

Ms. Rogien: I don't know. Oof. I wouldn't say no, but that would be more of an HBO question.

Ad Age: In dressing the Hannah character, do you have to take into consideration how much she takes her clothes off? How has impacted your dressing decisions for her?

Ms. Rogien: I think very carefully about any scene in which an actor manipulates wardrobe. Whether putting on a coat, getting dressed or disrobing on camera, I consider the emotional and logistical impact of the costume pieces. I try to ensure that the wardrobe supports the character and the emotion in the scene. Should it be funny? Should it be upsetting? Should it be sexy? I also make sure the wardrobe doesn't distract from what's happening in the scene, cause sound issues or take too long to put on or take off.

Ad Age: There was a fun moment in one episode this season where Marnie is interviewing for a position at an art gallery (the boss being Lena Dunham's mother) and she is asked where her suit is from and Marnie replies "Ann Taylor." That's obviously meant to reflect something about her personality right?

Ms. Rogien: Ironically the suit she's wearing is not actually from Ann Taylor! That line was ad-libbed on the day. We went after a suit that Marnie might have picked, and knowing that picking a suit was the exact wrong thing for an interview at an art gallery. It's an off choice... and it's meant to reflect where we all are when we are 25. I'm sure that's Lena and Allison's complete brilliance in the moment; and it's a realistic store for Marnie to consider.

Ad Age: I know you shop at flea markets and vintage stores a lot for the show, but if you had to assign a brand store to each character, what might it be?

Ms. Rogien: It's tough for me. One of my whole philosophies as a designer is mix and match. That's how you get a look that's real and a character who is a real person is to reflect the way people dress, which is to mix it up and match it up. It's about the right piece for the right character. Some of the girls wear similar vendors or brands but it's about the piece that's right for the character. Jessa is the toughest because she doesn't shop at stores.... She's more flea markets and Tibetan jewelry stores. She's the least-branded. Hannah's wardrobe too is a mix of vintage and thrift and the occasional on-sale retail item.

Ad Age: Can you remember your earliest shopping experience?

Ms. Rogien: I must have been four or five years old and it was the dead of winter in Montana and I decided I wanted to go shopping. I bundled myself up and my doll up and asked my mom for money. That might have been a good preview of things to come; I was very interested in shopping from an early age and had no concept of budget.

Ad Age: Tell us about your next project, "Orange is the New Black" and how your work will be different from "Girls." Where are you sourcing ideas and getting your inspiration?

Ms. Rogien: The story itself is based around a women's prison so we have done shopping with real vendors where we can. The episodes are intermingled with flashbacks so we have done everything from late seventies to early 1990s.... I have an amazing collection of vintage JC Penney catalogs and vintage Sears catalogs. We do a lot of reasearch for the flashback depending on the period. It's a huge cast because it's portraying inmates in a prison, and on any given day we have as many as 30 actors or guest stars in a scene in one day, which is pretty extraordinary.

Ad Age: You recently had a big brand announcement when you were brought on by Aerie to be a Style and Fit Expert for the brand. How did that come about?

Ms. Rogien: It was amazing timing really. I have shopped with them for years and they became aware of my work on "Girls" and my background on "Good Wife" and other shows drawing attention for their clothing. When the opportunity came up it was a good fit and I was really excited to join them. We shot a couple of videos introducing myself, put style tips up on the Aerie website. I've been previewing the collections with them and will be going into stores and doing some appearances.

Ad Age: What other brand possibilties are there for you? Any hints you can give us?

Ms. Rogien: I've got my hands full at the moment but keeping my eyes open. I've come to know a lot of brands through my work as a designer, so I'm always looking to partner with brands that you feel strongly about. And I'm a shoe lover, so that's something I'm always on the lookout for in work and personally [laughs].