Reid Carr knows when he goes to a networking event, his somewhat youthful appearance belies his professional credentials. “People will take a look at you, then look over your shoulder for the oldest person in the room,” says the 29-year-old founder and president of Internet marketing firm Red Door Interactive.

The age factor can work both ways. He’s never short on local executives willing to serve as mentors. “I seek advice where I can,” Carr says. “I’m looking for whatever experience I can get.”

Carr has chalked up some enviable expertise of his own. After working for other marketing firms, including San Diego’s McQuerter Group, Carr started Downtown-based Red Door in January 2002. With a staff of 30, Red Door’s client roster keeps growing.

Carr serves on committees for the San Diego Regional Chamber of Commerce, the San Diego Software Industry Council, the San Diego Telecom Council, the San Diego Venture Group, and by encouraging his employees to pursue volunteer work. Red Door does at least one pro bono project each quarter. Past beneficiaries have included Mama’s Kitchen, the National Brain Tumor Foundation and the San Diego chapter of the National Multiple Sclerosis Society.

“We’re really trying to make sure we have a well-rounded operation,” says Carr, who cautions against any assumptions that his inclusion on the “40 under Forty” list means his work here is done. “At 29 years, I hope to have a lot of good years before I’m 40,” he says.

Carr plays golf and participates in several soccer leagues, but doesn’t have much time for hobbies these days. He and his wife of six years, Amy, just welcomed their first child, George, on Aug. 1.