If you take a walk around the Arnold Arboretum on an autumn Sunday morning, you'll notice a group stationed at the Walter Street gate socializing.

They will be a diverse group, from a number of different backgrounds, aged from their mid-20s all the way up through their mid-60s.

Chatting, they give off the vibe of old friends -- and they are, as these social sessions occur several time over the course of the week.

And they will have just run 5 to 6 miles, a light run by their standards.

Parkway Running Club co-president Jim Sweeney said that the club's runs double as both training sessions for the area's runners and a social opportunity.

"We talk before, during, and after our runs," he said. "The atmosphere really isn't that different from a night out on a Thursday, Friday, or Saturday."

Keith Shields agrees. Shields is the race director for Walter's Run, the club's annual USA Track and Field sanctioned 5K that takes runners through West Roxbury in December.

"We're a group of friends who like to run," he said.

The club, according to Sweeney and his co-president John Govoni ("We couldn't decide, so we sort of just both took it," Sweeney explains with a smile), consists of members from West Roxbury, Roslindale, Jamaica Plain, Needham, and Dedham, amongst other locations. They estimate that the club, founded in 1994, has a membership of about 80, with 30 close-knit runners making regular appearances at runs. Much of the club's activity is based out of the West Roxbury YMCA.

Just because members consider each other close friends, have traveled together as far as Dublin to run, and celebrate a monthly "Thirsty Thursday" outing (usually at the Corrib), runners don't just join for the fun and games. Sweeney estimates that "about half" of the group's regular members have run a marathon. Sweeney himself has run 17, while Govoni has run 16.

"There's some training or coaching involved," Govoni says. "We have a lot of accumulated experience."

At-large member Ruben Carrizosa, a West Roxbury resident originally from Columbia, has run 10, as well as the treacherous Mount Washington Road Race. He explains his passion for running is "relaxing" and like "therapy," and appreciates having the support the group provides.

The club's vice president, Erin Dunne, thinks that the club's duel nature of high-level training and a social environment actually yields better results for runners.

"People can run faster, they just don't realize it," she said. "You just need to have friends to really push you along."

Shields says that runners interested in joining need not worry about their speed.

"I'd love to stress that a lot of people join running clubs thinking they need to be good," he said. "We always have runners of all speeds and all abilities."

Shields joined the club in 2000.

"Before I joined, I saw the club running but was too intimidated. I thought they were all track stars. But eventually I got out there with them and it's been a great time."

Govoni said the club makes sure to take care of all its runners on the course, regardless of their speed.

"We have a 'No Runner Left Behind' rule," he quipped.

The Parkway Running Club offers six weekly runs of different lengths and speeds. You can learn more about the club at http://www.parkwayrunningclub.org