This year's party drew more than 300 people, she said.
It was the fourth year Laurie and James Rickard of Cearfoss came to watch their daughter, 5-year-old Alissa, perform in the musical program.
Alissa really looked forward to singing "The 12 Days of Christmas" with her group, her mother said.
"She's been singing and practicing for weeks now. My kid's quite a card," she said.
The Rickards said they like the way the party and the programs mix the children and older folks, which seems to be good for both.
In a society where older people are often discounted by younger people, having the children regularly interact with older people shows them there's nothing wrong with getting old, James Rickard said.
"I think it's neat. It teaches the kids they can have just as much fun with older people as they can with kids their age," he said.
It was the first party for Debra Blossom of Williamsport, who came to watch 19-month-old daughter Jacqueline play a cookie in the program.
"She did great until she saw me," said Blossom, who said Jacqueline has been coming to the day care center on Fridays for about three months.
With her grandparents living in Indiana and Florida, Jacqueline doesn't have much interaction with senior citizens, she said.
"This is the most exposure she gets, which is what I like," Blossom said.
Daisy Cassidy, 79, said she loves coming to the annual party and singing with the children.
"It's fun. I love the children," said Cassidy, of Hagerstown, who participates in the adult day care program five days a week.
Cassidy said two of her seven grandchildren came to the party with her this year.
Bill and Linda Shelton of Boonsboro brought Bill's father, Lester Shelton, to the party.
The elder Shelton, 85, who has a form of Alzheimer's disease, has been coming to the adult day care since he had a hip replacement about three years ago, they said.
"It's fabulous. There are so many benefits. It keeps him busy. It keeps him active. It keeps his mind active," Bill Shelton said.
Bill Shelton said his father often comes home and talks to them about the children at the center.