Oddly, megachurch pastors mostly discovered their crossover appeal by accident — despite a reputation for marketing savvy.

"Originally, megachurches didn't seem to be reaching out to multiple groups, but they showed up anyway," said Michael O. Emerson, a Rice University sociologist who has done extensive research on race and religion. "They started having a voice, there was raised awareness, and the megachurches started feeling it was the right thing to do."

That was the path for Grace Chapel, located in a wealthy Boston suburb near the Massachusetts high-tech corridor. So many people attend Sunday services — about 3,000 — that the church has to run shuttle buses from two parking lots a half-mile away.

A decade ago, Grace Chapel was nearly all white, said Dana Baker, pastor of multicultural ministries. Now, Baker estimates that at least one-quarter of worshippers are minorities, with Chinese, Koreans and Haitians comprising the largest group.

"We saw the changing demographics and understood that something unique was happening here, and we wanted to be intentional about it," said Baker, who coordinates the church's multicultural outreach that started two years ago.

Paul Bodet, a native of Haiti who grew up in Miami, said he and his family used to attend a predominantly black church. But they switched to Grace Chapel for its preaching and its network for home-schoolers when his wife was teaching their two oldest children at home.

"We felt welcomed, but we did feel like we were one of the few minority faces," said Bodet, who works in the financial services industry and is now a church elder, or lay leader. "It's changed quite a bit since a couple of years ago."

Location matters. The Rev. David Anderson, founding pastor of Bridgeview Community Church in Columbia, Md., which has about 2,000 members, conducts what he calls the "Wal-Mart test" by driving to malls or Wal-Marts within a 20-mile radius of his church to see who's shopping.

"If the Wal-Mart is diverse," he says, "then your church can be diverse."

Anderson's megachurch is unique in that he started it specifically to be multicultural. He estimates that Bridgeview, more than a decade old, is now 55 percent African-American and about one-quarter white, with Asians, Hispanics and others making up the rest.

He also stands out because he is African-American. Most integrating megachurches are led by whites, and white Christians generally don't stay at black-led congregations, Emerson says.

Anderson, who trained at the prominent Willow Creek megachurch outside Chicago, said whites and blacks want different things from worship — in music and preaching — and "as a result, it doesn't take too long before people get weary and leave."

Anderson believes that could change if prominent white evangelical and black Christian leaders called on their communities to create multiethnic churches. Clergy who agree say the biblical imperative is clear — in Acts, which describes a wide variety of national groups in the early church, and the many verses that call for justice, mercy and reconciliation.

Modern-day inspiration can be found in an analysis of the 2005 Faith Communities Today survey, which found mixed-ethnicity congregations were more likely to grow.

David Ting, a physician at Massachusetts General Hospital and a Grace Chapel elder, has seen this firsthand. When he and his wife first joined the megachurch a decade ago, they were "very much in the minority" as Chinese-Americans, he said. But at a recent church Christmas pageant, he realized that the children's choir had transformed: about a third of the singers were Asian.

"Look," he told his wife, "this is the future of Grace Chapel."