Chris Burch, all of 5, could hardly be expected to know of the perils of homelessness: the nomadic life, the scourge of alcohol and drugs, the menacing streets, the anguish of a penniless existence.

But yesterday, when the young boy from Woodbridge bashfully described seeing a homeless man once, his mother asked if he wanted to help. "Yes," he replied.

"Good," she said. "I raised him right."

Chris and his mother, grandmother and 2-year-old sister joined more than 40,000 people yesterday in braving brisk temperatures under sunny skies in downtown Washington for the 15th annual Help the Homeless Walkathon.

After waking up in their heated homes, taking hot showers and grabbing a bite from a refrigerator full of food, the participants -- young and old, some with dogs -- covered 3.1 miles around the Mall yesterday to raise money and awareness for those less fortunate.

This year, several homeless advocates expressed concern that a change in rules for the event would result in less funding for their agencies.

The Fannie Mae Foundation, the event's sponsor, decided this year to strictly enforce a rule that it will pay matching funds only for registered participants who show up. Last year, it paid $40 in matching funds for each child and nothing for adults, but it did little to confirm whether they actually walked. This year, it tightened procedures and paid $20 per child and $20 per adult.

An agency's share of funding is directly tied to how much it raises for the event. Agencies said recruiting was hurt by last month's sniper attacks, and they had worried about getting people to show up on a Saturday.

"I'm a little disappointed," said Pascale Nouama, director of development at N Street Village in the District, which provides services to the homeless. "A lot of people on Saturday have children who have soccer or ballet, and they can't come. I think we should be a little bit more flexible."

Yet the amount of money raised yesterday should equal or exceed last year's $6.1 million, according to Stacey D. Stewart, president and chief executive of the Fannie Mae Foundation.

"An individual group may see a decline in funding, but overall, the funding for the program has not declined," she said.

The event was for a sobering cause: There are about 9,000 homeless people in the Washington area alone, and families make up 40 percent, according to the foundation. But the atmosphere was spirited. Teen star Mario sang on a stage at the end, and the honorary chairman, Chamique Holdsclaw, star of the WNBA's Washington Mystics team, walked the route.

At one corner, a mariachi band played festive tunes, and farther along, the Music Unlimited Dixie Trio belted out "Bill Bailey."

"How much farther?" asked Andrietta Minter, 16, of Haymarket.

"I offered to donate money instead of doing this," she said, "But I'm losing weight, and it's good exercise. I guess it's something different for a change."

Her mother, Mary Minter, 51, who brought Andrietta and two other children, ages 8 and 15, took the cause more seriously.

"We make it a point of coming out here. I think it's important for the children to see how fortunate they are," said Minter, a nurse. "There shouldn't be any homeless people in the United States, the richest nation in the world."

Some of the more than 40,000 walkathon participants gather for the start at Fourth Street between Constitution Avenue and Madison Drive NW.Four-legged friends keep up the pace for the 3.1-mile fundraiser around the Mall. Karen Shoemaker brought Jack, while Hal Burd walked Alex.