BRATTLEBORO -- The growth of Girls on the Run has administrators running to keep up.

That's why the Brattleboro-based nonprofit has hired more staff and moved into new, expanded offices while also implementing on-line registration and training as well as a third 5K run.

It's now estimated that Girls on the Run is reaching 25 percent of all girls in its target age group statewide. And in the organization's 15th year, Executive Director Nancy Heydinger said the program -- aimed at inspiring girls to be "joyful, healthy and confident" -- continues to sell itself.

"It just evolves because of word of mouth," Heydinger said. "People are loving the program. Girls want to participate. Coaches want to coach."

Added Annie Guyon, Girls on the Run's new marketing, communications and development director: "I will just walk around with one of our buttons on, and people will come up to me and say, 'I love Girls on the Run.'"

The international organization, founded in 1996 in Charlotte, N.C., employs a school-based, 12-week, 24-lesson curriculum each spring culminating in a non-competitive 5K run. Participants learn teamwork and, organizers hope, are given the tools for "physical, emotional, mental and social well-being."

"It's a way for them to expand their social circle and learn how to overcome peer pressure," Guyon said.

The organization's target age group -- grades three through eight -- can be "a really tough time for girls," she added. "This really gives girls concrete tools that they use every day."

Heydinger started the Vermont chapter of Girls on the Run in 1999 with a 15-member program in Vernon, and it's fair to say things have taken off from there. A sample of last year's numbers show how much the program has grown recently:

-- Girls on the Run Vermont added 37 new schools in 2013 -- a 20 percent gain from the previous year.

-- There were 282 new coaches in 2013, which raised the statewide coach count to 667.

-- Last year, 2,881 girls participated in Girls on the Run Vermont. That was an increase of 20 percent.

"Over the past 10 years, the intent has been to grow it," Heydinger said. "Now, it's taken on a life of its own."

But the program doesn't run on its own. And it became clear, Heydinger said, that Girls on the Run Vermont didn't have the space or the help to keep up with demand.

"We probably waited two years too long to add staff," Heydinger acknowledges. "We were trying to be fiscally responsible, but we were bursting at the seams."

Since last fall, Girls on the Run Vermont's staff has increased from two to five with the addition of Guyon, Cara Melbourne as program coordinator, and Leslie Myette, event director.

"We might need more," Heydinger said. "We're not sure we have enough staff yet."

The Girls on the Run staffers are occupying a new space: The nonprofit has moved from a 792-square-foot office in the Cotton Mill to 1,894 square feet in the former Book Press business complex.

That allows for more room to work and to store all the materials and supplies for a statewide program.

"We definitely needed that work space," Heydinger said.

Girls on the Run also is working more efficiently due to a new on-line registration system and an on-line training program for new coaches. The latter tool makes training shorter and more convenient for volunteers, administrators said.

"We travel around the state to do these trainings, so it's easier for us, too," Heydinger said.

There's been at least one other notable change: In 2013, Girls on the Run added a 5K run in Rutland to complement runs in Brattleboro and Essex Junction.

"That was something we needed to do to alleviate the pressure on the two existing 5Ks," Heydinger said.

This year's edition of Girls on the Run programs have begun, and about 3,000 girls are participating. With growth comes new challenges, and Heydinger said the organization's biggest challenge is finding and retaining enough volunteer coaches to meet the program's needs statewide.

Coaches are the lifeblood of the organization, Heydinger said.

"We have coaches who have stayed with us for over 10 years," she said. "They're so committed and wonderful."

More information is available at http://girlsontherunvermont.org.

Mike Faher can be reached at mfaher@reformer.com or 802-254-2311, ext. 275.