Ihsan Bagby of Shaw University in Raleigh, N.C., led a project in which the leaders of 416 of America's roughly 1,200 mosques were interviewed last year.
The survey was released in April and analyzed at length last weekend at a meeting of the Islam in America conference in Indianapolis. The meeting was organized by the Islamic Society of North America, one of the co-sponsors of Bagby's research.
The survey provided the first hard numbers on the extent of the faith in America. Today, an estimated 6 million to 7 million Americans consider themselves orthodox Muslims.
It also allowed Bagby to create a sort of snapshot of the life of American mosques.
Bagby said 77 percent of the imams and other mosque leaders his team interviewed reported increases in the number of regular participants over the previous five years, with 61 percent of mosques seeing 10 percent growth or more.
``We are probably experiencing the greatest growth rates of any faith group in America,'' said Bagby, a former United Methodist who converted to Islam 32 years ago.
Five percent of mosques reported declines, and Bagby said they tended to be smaller, inner-city and black.
Growth at U.S. mosques is coming largely in three ways, Bagby said. About 15,000 people a year are converting from other faiths, some Muslims are immigrating to America and others are beginning to practice their faith at mosques for the first time - often when the worship space is expanded, he said.
When Masjid El Fajr in Indianapolis expanded to accommodate 300 for prayers rather than 75, the mosque filled up the second week as word got out, Bagby said.
He linked mosques' sense of vitality to their strictness in following the Sunnah, the authoritative sayings and practices of the Prophet Muhammad.
Ninety percent of mosque leaders considered their congregations strict in this practice, and 79 percent considered their mosques spiritually alive and vital.
``There is a tradition that you feel you have to live up to. And the more you follow that tradition, the better you feel, the more alive you feel,'' Bagby said.
Mosques in the United States also are reaching out to their members and to non-Muslims in ways that go beyond prayer services, Bagby said. Three-quarters or more of those surveyed offered talks, classes in Islam and Arabic, and programs for women and children, he said. When it came to social services, at least 60 percent offered cash assistance to families or individuals, counseling services, prison programs and services to the poor.
While Muslims abroad generally worship only with others from the same ethnic group, the opposite is true in the United States, said Sulayman Nyang, who directs the Muslims in American Public Square project at Georgetown University's Center for Muslim-Christian Understanding. ``You will find a rainbow coalition of Muslims,'' Nyang told the conference.
However, Jimmy Jones, a panelist during a discussion on community involvement, said Muslims still must find a way to speak in a unified way on political issues. After some Islamic groups endorsed George W. Bush in last year's presidential election, many black Muslims resented it, he said.
``It is really a shame the so-called immigrant Muslims and the so-called indigenous Muslims don't work together more,'' said Jones, a professor of world religion at Manhattanville College in New York.
The mosque survey was cosponsored by ISNA, based in nearby Plainfield, Ind.; the Council for American-Islamic Relations based in Washington, D.C.; the Islamic Circle of North America in New York; and the Muslim American Society, the orthodox black Muslim group based in Chicago and led by Imam W. Deen Mohammed.
The project began by compiling a list of the 1,209 known orthodox mosques, and from a random sample of 631, leaders from 416 responded to phone interviews. The sampling margin of error was 5 percentage points. The project was planned by Bagby, Lawrence Mamiya of Vassar College and Mohamed Nimer of the Council on American-Islamic Relations. It was part of an interreligious study of 14,300 U.S. religious congregations sponsored by Hartford (Conn.) Seminary and funded by the Lilly Endowment.