Yellowberry founder Megan Grassell’s business crash course

April 22, 2014, 3:47 PM UTC
Yellowberry bras were designed by a teen for teens.

FORTUNE — The CEO is going to be late for class.

Megan Grassell founded her teen-targeted underwear company, Yellowberry, at 17 and now, as a high-school senior, she is trying to juggle a very full schedule of classes, extracurricular activities, and running a burgeoning business. “To say it’s taking over my life is a very small way to put it,” Grassell laughed during an interview with Fortune. “But I love it.”

It was during a trip to the mall with Mary Margaret, her younger sister, that inspiration struck: “I was shopping for bras at the mall with my mom and little sister, and we went to a bunch of different stores looking for a good first bra for Mary Margaret, but there was nothing. There were jogging bras or these very sexual padded, push-up bras. I kept wondering, where is the cute little bra in fun colors? I realized that it just didn’t exist. About a week later it hit me: If no one else is going to do it, I’m going to do it. I’m going to make bras for girls.”

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To fund her startup, Grassell raided her savings: “I worked every summer since sixth or seventh grade. First pumping gas and then I bussed tables and waitressed at a place called Nora’s, which is a fantastic restaurant. I saved all of that and used it to get my product to the prototyping phase.”

While Grassell throws around words like “prototyping” now, actually developing prototypes for her bras presented a steep learning curve for the teen. “Going into this process, I had no experience. I don’t even know how to sew! If I get a hole in my jeans, I’m out of luck, because I don’t know how to fix it,” said Grassell. “There are a lot of things that have to come together in order for a bra to be made. Sourcing the fabric was a challenge, finding out where to produce and who to work with. I didn’t know about quantities or anything. I had to learn all of that.”

To move from prototype to production, Grassell turned to the crowdfunding site Kickstarter. “The original goal was $25,000,” said Grassell, ”And I raised almost $42,000, which was pretty exciting.” It was also one of the most successful Kickstarter campaigns ever for an underwear or lingerie startup, ever.

With the Kickstarter campaign completed, Grassell found a production facility through a contact in her hometown of Jackson Hole, Wyo. The factory, which is in Los Angeles — and was vetted by her mom who was in California during one of Mary Margaret’s soccer games — has a low minimum order amount, which is good for a startup, but can also grow to meet increasing demand as necessary, which Grassell thinks is important. “If I get a phone call asking for a huge order, I will make that happen,” she said.

That can-do attitude is what people expect from a CEO, but not necessarily from a teenaged girl. Grassell admits that her age has been a challenge in doing business. “One of the biggest problems I had getting started was getting people to take me and my ideas seriously. I hope now they can see that I’m serious and that this is happening,” said Grassell, who comes across as a hybrid businesswoman: Half Rookie magazine editor savant Tavi Gevinson, half Spanx founder Sara Blakely. “I have a vision for the company. I know how I want it to grow, and I can’t wait to see how it becomes established.”

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Yellowberry is already on the market. At the company’s polished online shop, customers can choose between four styles, including “Bug Bite” and “Tiny Tetons,” names in line with the company’s motto: “From the bunny hills to the Tetons, we have you covered.” Yellowberry’s brightly colored bras are made from a cotton-spandex blend that is meant to provide a soft, comfortable transition between children’s undershirts and more adult bras. Needless to say there is nary an underwire in site. The bras are meant to give growing girls an option in the underwear market. “Yellowberry gives girls the idea that they don’t have to grow up so quickly,” Grassell said. “If they want to wear other bras, they can, we’re not saying what’s appropriate or not, but we want them to have another option.”

While launching and running a one-woman company (“My mom has been helping me recently,” she noted) and bringing a new product to market is challenging for anyone, Grassell has more on her plate than the average CEO. “The biggest challenge is that I’m still a full-time student, so the timing aspect has been really hard,” said Grassell. “I’m excited to be finished with my senior year in a few weeks so that I can truly work full time.” Grassell may end up deferring college — she’s been accepted at Middlebury College — for a year to focus on Yellowberry.

While Grassell may study business when she gets to college, she has already managed to do something that most MBAs dream of: She identified an unfulfilled niche in the marketplace and designed a specifically targeted product to fulfill the demand. As it turns out, her comfortable, well-designed cute products may disrupt the teen lingerie world.

It appears that there is a lot of demand for wholesome, age-appropriate, fun bras for tweens and teens. At the time of this article, Grassell’s product is completely sold out (“It’s a very good problem to have,” she said) and she is working to fill back orders as quickly as possible.

After calculus, of course.