WASHINGTON — Crips, Bloods and — Laura Bush?

In his State of the Union address, President Bush said his wife, a former librarian, would oversee a new $150 million, three-year program to assist at-risk youths ages 8 to 17 and help reduce gang violence and membership.

The job is Laura Bush's first official policy role, a recognition of her public popularity and a testament to her effectiveness as a campaigner for her husband and his causes.

Bush will take the traditional first lady's approach to the problem — highlighting the issue by visiting troubled areas and drawing attention to people and programs that steer children away from gangs toward positive, nurturing activities.

She made her debut in the role yesterday in Philadelphia, where she visited the Germantown Boys and Girls Club. Invoking her experience as a former elementary-school teacher and librarian, Bush emphasized that "the first five years of life are critical" to nurturing good behavior in older children.

"Research shows that boys who exhibit highly aggressive behavior as early as kindergarten have a greater chance of being involved in drugs and violence as adolescents," Bush said. She praised the Boys and Girls Club as the kind of community center where children can find strong role models in a safe environment where they can develop healthy values.

About 750,000 individuals nationwide belong to gangs, according to Justice Department statistics. More than 90 percent of gang members are male, but female membership is increasing, White House officials said.

Taking up a cause is nothing new for first ladies: Hillary Clinton hawked affordable health care; Barbara Bush promoted literacy.

But dealing with gangs is something new for Bush and the office of first lady. Her appointment turned heads among scholars who have viewed her as a more traditional first lady, in the mold of Bess Truman and Mamie Eisenhower.

"Other first ladies have been asked to undertake responsibilities; it's the topic that's new ground," said Myra Gutin, a communications professor at New Jersey's Rider University and an expert on first ladies. "I had always thought that Laura Bush would stay with education issues and literacy."

Lewis Gould, a retired University of Texas, Austin, professor who is editing a series of books on first ladies, suspects that Bush, like her husband, is trying to build a legacy.

"It is a departure for her," Gould said. "Mrs. Reagan would be the most notable example of a first lady's involvement in a youth program. I imagine she's [Laura's] concerned about her legacy, which has been indistinct over the last four years."