SAN ANTONIO - The noise of chatting parishioners saturates the foyer after the five weekend Masses at St. Mark the Evangelist Catholic Church.
Busy parents empathize with one another. Kids find new playmates. Singles meet other singles.
The tangle of conversations helps the church's 5,000 worshippers build a sense of community in a fast-growing congregation that decided five years ago to expand into a 1,500-seat sanctuary instead of splitting into two separate congregations.
The move was just one example of how Roman Catholic churches are joining their Protestant counterparts across the country in creating megachurches - where thousands, sometimes tens of thousands of congregants worship together. But unlike the Protestant churches that use high-profile, evangelistic campaigns to grow, dioceses say too few priests and too many worshippers drive their expansion.
While the number of worshippers per parish nationwide has grown by nearly 35 percent in almost three decades, the number of priests dropped 26 percent, said Mary Gautier with the Center for Applied Research in the Apostolate at Georgetown University, which tracks trends in the U.S. Catholic Church.
"That's the reality in the Catholic Church today: You don't want to build something that will be OK for now, when you know this large population is going to get bigger," Gautier said.
Dioceses in the South and West - the hot spots for new jobs and suburban sprawl - are primarily the ones building larger parishes; they're increasingly filled with Hispanic Catholics, many of whom are immigrants, Gautier said.
The Midwest and Northeast are generally consolidating, Gautier said, due largely to population shifts to other regions of the country.
Gautier said several dioceses, including the Archdiocese of San Antonio, seek at least 1,000 seats in design plans for new or expanded sanctuaries. Most sanctuaries used to be built with about 500 seats, she said.
In San Antonio, at least 15 sanctuaries have doubled or tripled to at least 1,000 seats in the past eight years.
"We didn't want to put two parishes in the same town because we just didn't have the priests to do it," said Monsignor Larry Stuebben, vicar general of the archdiocese.
Making a church bigger increases the need for financial commitments but it also drives down the average cost per church member, according to the Georgetown research group.
The research group estimates that it costs $444 per household nationwide for membership in churches with fewer than 800 parishioners, compared to $337 for those with more than 1,000. The extra congregants help cover the cost for more paid, lay staff - who are increasingly picking up administrative duties to free priests for pastoral and sacramental duties, said the Rev. Larry Christian, rector of Assumption Seminary in San Antonio.
"You have to have a large enough economic base to make that happen," he said.
The 65 million-member U.S. Catholic Church has generally tried to avoid the "megachurch" model, like Joel Osteen's Lakewood Church in Houston that took over the former arena for the Houston Rockets NBA team and fills it each week with more than 30,000 congregants.
The U.S. Conference of Catholic Bishops advises parishes to avoid "any semblance of a theater or an arena" in worship settings.
While new Catholic churches are designed with a larger seating capacity, the pews are curved around the altar so people don't lose a sense of intimacy during worship, said Jim Moroney, head of liturgy for the Catholic bishops conference.
"The challenges are indeed significant," Moroney said. "But we want to create sight lines to see the whites in someone's eyes when we're preaching to them."
And large parishes are offering more programming, especially Bible study and social action groups, so members meet one another and create a community within a community, Moroney said.
That programming makes them more like Protestant megachurches, said Scott Thumma, who specializes in megachurch research at Connecticut's Hartford Seminary.
The nation's 1,200 Protestant megachurches, defined as having at least 2,000 weekly attendees, make small group participation the crux of their organizational structure, he said.
"Anything that goes beyond just a large gathering - such as using small groups to create a congregational life with their members, that's a significant shift in the organization of a Catholic congregation," Thumma said.
St. Mark advertises its 40-plus ministries and small groups on a large sign over the main entrance to the sanctuary, including a first-ever Bible study that breaks members into groups of eight to 10.
"Once a person makes a connection by putting their name on a list or talking with a leader, then I feel its our responsibility to pick up on that connection," said the Rev. Kevin Ryan, the St. Mark pastor. "We are trying to break down our community into smaller groups."
The church considered splitting into two congregations in the early 1990s because regularly 200 people would have to stand in aisles in its 750-seat sanctuary during its weekend Masses, longtime member Marybeth Green said.
"It was competition to get a seat and parking spot," she said, "and that's not the Christian spirit. (The new sanctuary) represents faith that we could still serve the people who come."