Main Line native and Blackwood resident Susan Collins had just left a long career in home building when she read about a women's group that would change her postretirement life.

Founded in 2000, the group, the Transition Network (TTN), boasts 12 chapters nationwide, with two more forming. It seeks out women age 50 and up, particularly baby boomers, the first generation of women to leave the workforce in huge numbers.

Why a network for women facing retirement?

Collins says TTN helped her move into the next phase of life.

She got her bachelor of science in marketing from Rutgers-Camden and worked for Pulte Homes and other builders for almost 20 years. In 2007, she retired - without much of a plan.

"I knew I was leaving the stress and the paycheck. I didn't expect to leave the totality of my life - everything I thought I was turned out to be wrapped up in what I did," she recalls.

Suddenly, after managing 65 people, "no one was asking my opinion. There was nobody to lead or inspire, and social connections drift away," she says.

Collins spotted a small advertisement in, of all places, AARP's magazine, highlighting a new community of professional women called the Transition Network.

"I'm not a joiner, but something about it resonated," she says.

In 2009, Collins attended her first TTN meeting in Center City, hosted by Mary Klein and Ellen Singer Coleman. Klein and Coleman wanted to help each other and other women after retirement, so they set up a Philadelphia chapter of the Transition Network.

"Mary Klein greeted me like she'd been waiting all day. She was welcoming and interesting," Collins says.

The next meeting blossomed into 50 women, Klein says. They hosted magazine writer Carol Saline, who gave a hilarious talk - "Don't Be Waiting at the Bus Station When Your Train Comes In."

TTN members divide up into peer groups, based on geography or interest. Klein joined the Mount Airy and Center City peer groups.

Collins was impressed.

"This wasn't just gals shooting the breeze. It was women who wanted to create something meaningful," Collins says. She got involved as secretary, and "listened and learned. I had to do something useful and got involved in national initiatives in 2010 and 2011. By 2013, TTN nationally was looking for an executive director, and I realized I wanted the job."

Most retired women who join now didn't live the same lives as their mothers, who typically did not work outside the house.

One woman, Collins recalls, remarked at an initial meeting, "Yes, I can fill up my calendar with dinners and movies and my grandchildren. But really, what's the point?"

Collins could identify - and so can lots of other women. Today, TTN's Philadelphia chapter counts 275 members, up from just a few in 2009. Since the national organization's founding 15 years ago, it has grown to 2,100 members, and the average member's age is 62 to 63.

"What are you ending or leaving behind? We experiment and discover what's meaningful," whether that's volunteering, museums, or travel, says Klein. Last year, TTN hosted author/actress Marlo Thomas.

The next event is "Happy Volunteers" on Nov. 17 from 5:30 to 7 p.m. at the Tivoli building, 1900 Hamilton St.

A "Women in Transition" workshop for new members is set for Nov. 20, starting at 8:30 a.m., at the same location.

To register, send an email to: philadelphiachapter@thetransitionnetwork.org. For more information about the group, visit thetransitionnetwork.org.

Jean Brubaker, who calls herself a "partially retired" photographer and marketing/public-relations consultant, joined TTN in 2009 after coming to one of the first events.

"I met Mary Klein and others, and I was hooked," Brubaker says.

As part of her discovery of her new interests, she is now entering the second year of the guide-training program at the Philadelphia Museum of Art, "which is challenging, immensely enriching, intellectually rewarding, and time consuming."

The enemy in retirement?

Klein calls it "the big empty space."

"As soon as you retire and don't know what to do next, you get that panicked feeling that the day is arrived: 'What do I do with myself?' " Klein says. "We see a lot of women dive into TTN. They substitute us for their work and for the watercooler."

215-854-2808@erinarvedlund