They prepared meals and delivered gifts, visited nursing homes and packed bags for children in foster care.

In a crowded workroom at the Jewish Community Center in Squirrel Hill, they decorated holiday greeting cards for the sick, an army of mostly Jewish volunteers for whom Christmas Day was Mitzvah Day -- celebrated through community service.

More than 425 people took part in projects throughout the city to benefit dozens of social service agencies as a way "to give our non-Jewish friends the holiday off," said Stephanie Brenner, an organizer with the United Jewish Federation, which runs the yearly day of volunteering.

Mitzvah, in Hebrew, is generally defined as a good deed.

"And it's not only a good deed," Ms. Brenner said. "It's doing something and not expecting something in return."

The smell of Elmer's glue wafted through the air as 7-year-old Justin Tannenbaum, in a flurry of glitter, crafted a New Year's card for a patient at Allegheny General Hospital whom he did not know and would probably never meet.

Anonymity was OK, he said.

"I just think that some people might need something, and I just give it to them and make a card," Justin said. In this case, his card bore a simple message, "Happy New Year, from Justin," and showed a glittery ball preparing to drop. "I just give them really good stuff."

The Tannenbaums, of Squirrel Hill, have celebrated Mitzvah Day before, though it was a first for 4-year-old A.J. Their mother, Lisa, recalled the joy she saw in her own grandfather when he received holiday cards from children at the VA hospital last week.

"I'm just kind of picturing him," she said.

Sitting at the next long, plastic table was Rabbi Barbara Symons, who snipped snowflakes from white construction paper and reminded her family that a mitzvah is also a commandment from the Torah, such as visiting the sick. Greeting cards for the sick, she said, were the next best thing.

Volunteering alongside her were her daughter, Ilana, 12, and relatives in from Buffalo, N.Y.

"The side effect is the Jewish community comes together," said Rabbi Symons, of Temple David in Monroeville. "It sends a message of what a difference can be made when we work together."

In a quiet room across the hall, a small group gathered around a table making booklets of quotations for women in Hearth, which provides housing and other services for individuals and families.

In marker, Emily Farkas, of Morningside, labeled her book "Words of Encouragement," and penned quotes on each of its pages. She didn't know the women who would read them, but chose words she found reassuring.

"It's an anonymous way to make someone's day a little better," she said.

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