A Muslim homemaker from the Los Angeles area, assuming authorities monitor her charity donations, has stopped giving to “any Muslim charity that touched my heart” and now contributes to less-controversial organizations.

In Sacramento, Calif., a young imam has broken with an ancient tradition among Islamic prayer leaders by shaving part of his beard to appear less threatening to non-Muslims.

Since Sept. 11, 2001, they say, increased scrutiny and suspicion have made them more cautious about expressing their faith. Other California Muslims have taken a different approach.

A 19-year-old hijab-wearing student at the University of California, Irvine, and others in her school’s Muslim Student Union staged a program in May critical of Israel called Holocaust in the Holy Land. She also helps organize rallies and fundraisers to support Muslims that she believes have been unfairly targeted by federal investigators.

The experiences of the homemaker, the imam and the student reflect the transforming and sometimes contradictory effects of the Sept. 11 terrorist attacks. In the five years since the attacks, some Muslims have tried to be less visible, others more bold, as they live and work beside their fellow Americans.

“We are witnessing the creation of a new Muslim-American identity that is still a work in progress,” said Zahid H. Bukhari, director of the American Muslim studies program at Georgetown University.

“In times past, it happened to African-Americans, Latinos, Jews, Japanese and Catholics; now, it’s Muslims’ turn to become part of the fabric of American life,” he said.

Many who study US Muslims say that, without the Sept. 11 attacks, it might have taken the extremely diverse, reclusive and largely immigrant community — an estimated 6 million to 8 million — another decade to enter the public square. The acts of terrorism on US soil forced them into it, albeit under what some Muslims believe are the prying eyes of government, media and neighbors.

They speak of shifting to unlisted telephone numbers or obtaining post office boxes so they don’t have to reveal their home addresses. Some have even stopped going to mosque prayer meetings.

“It’s an amazingly exhausting job being Muslim in America these days, because we’re always on,” said Napha Phyukal Quach, a congregant of the Al-Fatiha Islamic Center in Azusa, Calif.

Zubeida Khan immigrated to the United States from India in 1977, under terms of a family-arranged marriage, to wed Iftikhar Khan.

Her husband went on to become a cardiologist. In 1998, the couple and their two sons moved into a spacious hilltop home 15 miles east of Los Angeles.

For years, “I was content being a housewife,” said Khan, who does not cover her hair with a hijab but always dresses modestly, in long-sleeve blouses and long skirts or pants.

Then came Sept. 11.

“With people being arrested left and right and negative images of Muslims filling the news, I told my sons to keep a low profile,” recalled Khan, 49. “But I also felt I had to step out of my home and into the real world to stand up for Muslims and tell people what Islam really stands for: Peace, mercy, equality for all. Surrender to God.”

Khan began inviting people who might help promote understanding — city officials, pastors and rabbis — to her home for face-to-face talks. She joined the Muslim Public Affairs Council Foundation in 2003, and now serves as treasurer of its board.

“In becoming more assertive in the public arena, I’ve made a statement about who and what I am at a time when a few unreasonable radicals have hijacked public attention,” she said. “We have to make it loud and clear to other Muslims and our communities that we stick to the principles of the Qur’an and the life of the Prophet.”

Marya Bangee, the student at UC Irvine, says she, too, is trying to embody the principles of Islam. But she is among those who take a more aggressive approach when engaging American society.

Civil rights have become a banner issue among many Muslim youths. Unlike their parents, many of whom came from countries where political activism could be dangerous, today’s students know their rights, speak the language and know American culture.

Among Bangee’s recent priorities has been campaigning on behalf of an Orange County, Calif., fundraiser jailed for two years because of his connection with a charity allegedly tied to terrorists. On July 27, a jubilant Abdel Jabbar Hamdan was ordered freed by a federal judge who rejected the government’s claim that he was a national-security threat.