A national behavioral-health agency intends to open a shelter that will house up to 42 undocumented migrant children in the affluent Chester County community of Devon.

Angered by the plan, neighbors say they initially learned from workers who were renovating a shuttered Devereux Advanced Behavioral Health property that youths who crossed the nation’s southwest border alone, or were separated there from their parents, would be moving in soon. The detention of those children, deemed “unaccompanied minors” by the federal government, has helped fuel the heated national debate over immigration.

“The staff at Devereux believe it is our moral and ethical imperative to provide the highest quality care for any and all children in need,” Devereux executive Leah Yaw said in a statement Tuesday. “It is unthinkable to Devereux staff that we would sit by and not do everything possible to provide aid, comfort and meaningful supports to hurting children.”

The nonprofit agency plans to use its Stone & Gables campus on Highland Avenue for the shelter. Neighbors said they were told that homes would be built on the site, though Devereux says that was discussed only as one option.

Yaw said the shelter would house children ages 5 to 12, with no set date for their arrival. The shelter is still in the planning stage, she said, and particularly after residents raised concerns and opposition at a Monday night meeting of the Easttown Township Board of Supervisors, attended by about 40 people.

Residents promised to challenge the zoning for the shelter, to block it from opening.

“We heard really clearly we have community work to do, and community relationship-building to do,” Yaw said in an interview Tuesday.

She said the agency has told federal authorities that Devereux believes the deliberate separation of families is “an aberrant practice, which should never happen," and that Devereux would not support or be involved in that.

However, conditions at the border can make it difficult or impossible to determine who is truly “unaccompanied.” Generally, that term refers to a child who comes to the country without a parent or legal guardian. But lawyers and investigators have reported that children who enter the United States with an aunt, uncle, or other relative who is not a parent are being separated from those family members.

About 20 miles northwest of Philadelphia, Devon is home to 1,700, a population that is 92 percent white. The median income is $183,483, more than three times the state median of $56,951, according to Census figures. It’s probably best known for the annual Devon Horse Show and Country Fair, among the jewels of Main Line traditions.

Devereux bills itself as one of the largest and most advanced behavioral health-care organizations in the country. It was founded in 1912 by special-education pioneer Helena Devereux, and today employs more than 7,500 people and operates 15 centers in 13 states.

In recent weeks, Devereux has been running online employment advertisements that describe its plans:

“In response to the humanitarian crisis at America’s ports of entry,” the ads state, “Devereux will be providing short-term shelter care services for refugee children who have come to the United States without their legal guardian.”

The initial government payment of $14 million will support the project in Devon but also help Devereux plan and potentially open four new migrant children’s shelters around the country — in Connecticut, Texas, Colorado, and Massachusetts — along with a small foster-care program in New Jersey that will have no physical campus.

The detention of migrant children has been highly controversial, and a $14 million initial payment shows again how the housing of undocumented migrants has become big business in the United States.

An Arizona-based for-profit agency, VisionQuest, is to be paid $5.3 million over three years to house 60 undocumented migrant boys in North Philadelphia. That project has stalled in court, as city zoning officials have denied approvals and opposition has grown among neighbors, the teachers’ union, and City Council members who say a “sanctuary city” should not confine migrant youths within its borders.

VisionQuest is planning to open another shelter for unaccompanied migrant youths in Albuquerque, N.M., garnering at least $2.9 million in federal monies. And a program in South Jersey also is earning millions.

Many of the children whom the federal government identifies as unaccompanied minors have fled gang violence and poverty in Central America. They have no parent or guardian in this country, and are held by the government as it seeks to place them with relatives or sponsor families.

“This is apolitical for us,” Yaw said. “At no point did we think this would be an easy thing to do. We understand the complexity. We just thought it was the right thing to do."

The children who would be coming to Devon have no identified special needs or disabilities, and no behavioral problems, but at the same time need care and support for trauma suffered during their immigration journeys, she said.

Juntos, the Philadelphia-based Latino advocacy group, immediately spoke out against opening a children’s shelter in Devon.

“With the backlog in the courts, many kids run the risk of being detained indefinitely,” said Erika Almiron, Juntos’ executive director. “There is no real accountability that happens if people are not aware of these centers being opened in their own backyards.”

Juntos urged the agency to “abandon their plans to lock up immigrant youth.”

Devereux’s job advertisements sought a bilingual youth-care worker, administrative staff, food-service workers, shift supervisors, and a bilingual education director, among other positions, to help “provide extremely high-quality, trauma-informed residential and educational services for refugee children, with intense supports for their social and emotional health.”

The goal, Devereaux said, is to ensure that “every refugee child who receives our services is successfully and quickly discharged into the loving care of their family sponsor,” and in the interim receives medical, therapeutic, and educational services “specifically to address the traumas they have sustained during, and often before, their migration journey.”