The Devereux Foundation plans to close its adolescent behavioral-health program in Willistown on Dec. 14 and lay off up to 150 workers, one-tenth of its staff in Southeastern Pennsylvania.

The announcement came as the Villanova-based nonprofit, a leading provider of mental-health treatment for children and adults, prepares to celebrate its centennial anniversary in November.

Maggie McGill, chief operating officer, said the adolescent program for up to 55 teens had been underfunded for years.

"Our expenses are more than what our payers have been able or willing to pay," she said. "We've been supplementing the cost of care in that program, and we simply cannot continue to do it."

The residential program is based at the Mapleton campus, which also is home to a 30-bed psychiatric hospital. That facility may be expanded to 45 beds, McGill said.

She added that the foundation was looking at saving part of the adolescent program, but said it was premature to go into details. Clients typically receive treatment for less than a year.

"We're coming together with some people," she said, "to see what we can do right now."

Reimbursements from Medicaid and private insurers, she said, had been flat for years.

"It's difficult for state and local governments even to keep up with inflation for health-care costs for employees," she said.

The organization is trying to place teachers, direct-care staff, clinicians, and administrators who will lose their jobs at other Devereux facilities in Pennsylvania and across the country. McGill said she doubted that all of them could be accommodated, "but we're certainly going to try our best."

Devereux was founded by a young Philadelphia teacher, Helena Devereux, who took a special interest in students who were considered "slow." She believed that each student could learn in an environment tailored to his or her needs.

Devereux employs 6,000 people and serves more than 15,000 people annually from 43 states and five foreign countries in a wide variety of settings, including group homes, schools, and four campus-based programs in the Philadelphia area.

Contact Kathy Boccella

at 610-313-8123 or kboccella@phillynews.com, or follow on Twitter @kmboccella.