NASHUA – In her regular life, Rosalie Prince is an office administrator with BAE Systems. On Tuesday, she took on a different role, cleaning and organizing closets at St. Joseph Community Service on Temple Street.

“This is the most rewarding experience you can do,” Prince said. “You give your personal time, and it’s to people you don’t know.”

Prince was one of more than 330 volunteers who spent the day helping out at Nashua area nonprofits as part of the United Way of Southern New Hampshire’s 21st annual Day of Caring.

From painting bedrooms at Nashua Children’s Home to packing boxes for the Cystic Fibrosis Foundation’s upcoming events, the volunteers spread themselves across more than 50 sites.

Many employers supported the event, bringing together teams of workers to spend the day helping in the community. Prince said BAE has been involved in the Day of Caring for years, giving about 50 employees paid time off to work for the nonprofit groups. BAE also sponsored a fundraising drive leading up to the day, pledging to give up to $10,000 to the United Way chapter’s annual campaign based on the involvement of others in the area.

UPS supported the event by encouraging volunteers to “stuff” its “flame truck” with nonperishable food, sheets and other donations for local agencies.

The staff of participating nonprofits said the annual event is valuable both for the work the volunteers do and for the chance to expose more people to the organizations.

“They get an appreciation for what we do and an understanding, and we get the help,” said Melissa Dunkle, assistant site manager at St. Joseph Community Services Senior Activity Center.

At various sites, the nonprofit groups used the day as an opportunity to inform the public about issues affecting their work. As Dunkle brought several volunteers to help prepare food for the Meals on Wheels program, she mentioned that deliveries would be reduced from five to four days a week because of lower state funding levels.

“We’ve had a lot of cuts,” she said.

At Head Start, family engagement coordinator Heidi Toursie told volunteers there is a wait list of more than 20 families looking for day care for part of the day for their children that the organization can’t accommodate. She said many people are misinformed about the situations of the low-income families her group serves, and she wanted to let the volunteers know that almost all the families she deals with are eager to work and to make better lives for their children.

“I feel it’s our responsibility, as the people working on the front line with these folks, to dispel some of those rumors that aren’t true,” she said.

Kara Siwik, a nursing aide at Southern New Hampshire Medical Center, said she was excited to return as a volunteer after taking part in last year’s Day of Caring. Last year, she said, she rode along with a Meals on Wheels delivery driver.

“I enjoyed meeting the people one on one,” she said.

Siwik said she found the experience “humbling,” particularly when she discovered they were doing a delivery for a patient of hers who turned out to be living on the second floor of an old barn building.

“To find the situation he was living in was heartbreaking,” she said.

The Day of Caring concluded with a barbecue for participants including a raffle of items donated by local companies. Mayor Donnalee Lozeau was on hand to present the local United Way’s Max I. Silber Community Service Award to the Rev. James S. Chaloner. Chaloner has been the pastor of the First Church of Nashua since 1978 and a member of the United Way of Greater Nashua board of directors since 1999.

The event also marked the formal start of the organization’s 2012-13 fundraising campaign.