By Suzanne Perry

President-elect Barack Obama today unveiled a new television advertisement as part of a push to get Americans to make a year-round commitment to community service.

“America’s greatness was not crafted in skyscrapers alone, but on the ground by those who could see what needed to be done,” Mr. Obama says in the public-service advertisement, “Step Forward,” which was created by the Presidential Inauguration Committee and the Advertising Council.

The ad refers viewers to a new Web site, USAService.org, that allows people to post and sign up for volunteer activities in their communities. The site is part of a program, Renew America Together, that was announced on Friday by Colin Powell, the former secretary of state who is honorary co-chair of the January 20 Inauguration.

General Powell—the founding chairman of America’s Promise Alliance, a coalition of children’s-advocacy groups—told a news conference that the program seeks to get people across the country to volunteer on Martin Luther King Jr. Day, which has been a national day of community service since 1994.

Mr. Obama, Vice President-elect Joe Biden, and their families plan to do volunteer work in the Washington area on the holiday, which falls one day before the Inauguration, he said. But Mr. Obama also wants to inspire people to stay involved for the rest of the year, General Powell said.

“It is not enough to just do it one day a year,” he said. “What we really need are Americans to come forward and leverage up the great capacity that exists in this society by committing themselves to a voluntary activity on a regular basis.” General Powell called the new Web site a sort of “craigslist” that will match people with existing volunteer programs, or allow them to start efforts of their own.

Nonprofit groups and others have already registered almost 6,000 volunteer events on USAService.org.

While previous administrations have promoted community service, Mr. Obama will be able to “take it to a new level” because of the enthusiasm his campaign generated, Mr. Powell said. “I think there’s a fervor to the new administration coming in,” he said. “I think the President-elect can tap into that enthusiasm, fervor, with this program.”

The Advertising Council is distributing the new television ad—as well as public-service radio ads—to stations across the country this week. Several broadcasters have already agreed to donate time for them, including CBS Television and Radio, Clear Channel Radio, CNN and the Turner Networks, Comcast Spotlight, Entercom Communications, Fox Networks, and NBC Universal, the inaugural committee said.

Mr. Obama will make an additional pitch for community service on Inauguration night, when he is scheduled to appear at the Youth Inaugural Ball, reserved for people ages 18 to 35. He will make remarks there for a live broadcast sponsored by ServiceNation, a coalition of 120 mostly nonprofit groups, and MTV, the cable television network. “Be the Change: Live from the Inaugural,” will air at 10 p.m. Eastern time on January 20.

Service Nation is also sponsoring a breakfast on Monday, January 19, to celebrate “A New Era of Service.” Speakers will include Martin Luther King III; Adrian Fenty, Washington’s mayor; and the film actors Tobey Maguire, Demi Moore, and Ashton Kutcher. Ms. Moore and Mr. Kutcher will show a video message from entertainers pledging to do community service. Richard Stengel, managing editor of Time magazine, will moderate a discussion on service.

Following the breakfast, participants will work on a project to beautify a school in one of Washington’s poorest neighborhoods, Simon Elementary School.