It’s grown to be an annual holiday favorite in Lawrence, and it helps a good cause.

Shelter Inc. is auctioning off donated Christmas trees for its Festival of Trees event Dec. 2 at Liberty Hall, 642 Mass.

“It kind of gives you a warm, fuzzy feeling inside,” Liberty Hall manager Tim Griffith said of the event.

The trees can be viewed from 10 a.m.-8:30 p.m. Nov. 30-Dec. 4. On Dec. 2, the trees are open for public viewing from 10 a.m. to 5 p.m., and the auction begins at 8 p.m. Admission to the auction is $25.

Shelter Inc., a nonprofit organization that helps troubled teens who otherwise would have to live in foster care, has two emergency shelters with 14 beds that youths can stay in for 90 days. The organization also runs an adoption agency and does crisis interventions.

“That’s the good thing about Lawrence,” Griffith said. “Lawrence usually tries to take care of its people.”

Event organizers hoped a poor economy wouldn’t limit the number of donations.

“I’m sure that’s entirely possible that that could occur,” said Judy Culley, Shelter Inc. director.

Culley said the event wasn’t about money.

“People want to help kids, and they don’t always know what to do to help,” she said. “What I really like is the goodwill that is generated from it.”

Last year, Shelter Inc. raised $34,767 from the fund-raiser.

Gail Vick, co-chair of the festival, has been a part of the event for three years.

“It just really gets you into the Christmas spirit,” Vick said.