PORTLAND, Maine — Teenagers arrive at Preble Street’s Teen Center or Lighthouse Shelter for a wide range of reasons. Abuse, sexual abuse, trouble with the law, family crises. But once they show up, none are turned away.

“Anybody under 21 who walks through our doors can get their basic needs met,” said Chris Bicknell, director of the teen center. “[We don’t put up] barriers to youth who have been rejected by other programs. Our kids have been kicked out of schools, they’ve been incarcerated, they’ve been kicked out of their homes, they’ve been kicked out of their foster homes and group homes — almost everywhere they’ve been, when they’ve been in a crisis, their behaviors weren’t tolerated.”

The “low-barrier” approach to providing services to the homeless and poverty-stricken — of any age — has always been central to Preble Street’s philosophy. But now, with the economic benefits of open arms becoming more statistically clear, the Portland organization is becoming highly sought after to explain their methods and best practices on a national stage.

“The cost to the city of [a homeless person] being here is far less,” said Caroline Partlow, coordinator of Preble Street’s Logan Place, an apartment building for the chronically homeless where operators embrace some of the most troubled tenants in the city. “They used to be in the shelter or the emergency room or the county jail.”

Preble Street leaders have been increasingly called on in recent months to conduct online seminars for the U.S. Interagency Council on Homelessness and the Runaway and Homeless Youth Training and Technical Assistance Center. The center is calling Bicknell down to another conference in Baltimore this summer.

Closely linked with the low barrier model in the industry vocabulary are “harm reduction” and “housing first” philosophies, in which service providers accept that small steps toward healthier lifestyles are better than none, and that providing stable housing for someone battling mental illnesses or abusing substances is a crucial first step toward recovery. None of these approaches were historically the industry standards, Preble Street officials say, as many service providers nationwide have long required tenants or clients to stay clean for long stretches before qualifying for help.

Mark Swann, executive director Preble Street, noted that The Shaw House and Bangor Area Homeless Shelter in Bangor use low-barrier approaches for some programs, as does New Beginnings in Lewiston.

“Folks running high-barrier programs — ‘You’ve got to stay sober to come here, you’ve got to take your medication to come here’ — they’re very afraid of a loss of control,” Bicknell said. “But if we turn that kid away, they’re more likely to use more drugs, more likely to sell their body for a bed for the night, and they’re less likely to survive adolescence. If we can eliminate the need to take those extra risks, that’s automatic harm reduction.”

Preble Street Associate Director Jon Bradley said the organization takes in all comers, regardless of their demons, because “if they’re here, we can work with them.”

“It’s like the old mission houses of hundreds of years ago,” added Swann, who last week was named a finalist for the prestigious Congressional Medal of Honor Foundation’s Service Before Self Honors. “They threw the doors open and that started the conversations.”

Thomas McLaughlin is an associate professor at the University of New England and the co-director of the Social Work Center for Research and Evaluation. His work over the last five years, in partnership with Preble Street and Shalom House Inc., is considered to be among the first analyses in the country to quantify the public savings generated by investing in low barrier and housing first programs.

“There actually is a cost to doing nothing, and mostly it’s emergency services,” McLaughlin said. “They’re pretty expensive.”

For his study, McLaughlin’s team followed nearly 100 greater Portland homeless individuals with disabilities — receipt by receipt — and compared their draw on public money before being provided stable housing and after. In 2009, he reported that, in their second year in stable housing, the subjects cost taxpayers a total of $622,386 less than in the year prior to entering the housing.

“Five years from now, these statistics might be well accepted,” McLaughlin said. “But for now, it’s new for social workers to be talking about things in terms of dollar figures.”

The cost avoidance came primarily in more efficient use of medical care and fewer run-ins with law enforcement, according to McLaughlin’s study, with year-to-year drops of roughly $264,000 and $188,000 in health care and mental health care costs, respectively. The greater Portland subjects also consumed nearly $85,000 less in police, ambulance and jail resources, saving the government more than two-thirds of what those same individuals cost in law enforcement and rescue resources the year before entering the stable housing program.

“It’s people jumping from detox to the shelter to jail to the hospital,” Swann said. “That’s not only expensive, it’s ineffective. One year we had 26 memorial services for people who died on the streets. We had to ask ourselves, ‘Is this the best we can do? Let these people bounce around from place to place and then die?’”

McLaughlin said his research doesn’t take into account the harder-to-quantify economic impact of turning a heavy public service user into a net positive contributor to the community.

Kevin Bowshier is a resident of Logan Place, one of a number of facilities and programs now run under Preble Street’s umbrella. He’s been at the seven-year-old Frederic Street apartment building now for about a year. He said he’s given up smoking and drinking, his long history of run-ins with police has come to a halt and, with the help of building staff and partner agencies in the city, is regularly taking medications to control his mental illness.

On one evening last month, he sat in the building’s community room downstairs listening through headphones to a new CD he purchased that day on a walk to a nearby shopping center. He bragged to a reporter about finding a great deal on a home exercise machine after paying a recent month’s rent. Preble Street officials note that, with a prohibitively high price of admission to their programs, individuals like Bowshier wouldn’t be circulating notes in the local economy, but rather knocking on the doors of public overnight shelters or hospitals.

Logan Place “helped me stand up on my own again,” he said.

Back at the Teen Center, 19-year-old Adym Verrill said she started coming to the center for stability nearly two years ago, just before becoming “fully homeless.” Since then, she’s acquired her GED through classes offered at the center in partnership with the Portland Public Schools, and she plans to enroll this month at the Empire Beauty School branch in the city.

Ashlee Richards, 20, is pregnant with her second child and said she’s eager to work with Teen Center counselors and their partners to find her own apartment, find a job and begin taking college classes to become a veterinary technician, something she said she never before thought was a possibility.

“I didn’t think college was really an option before coming here,” she said.

“It gets complicated when you start talking about money,” Bradley said of efforts to gauge the costs and benefits of low barrier and housing first models. “What’s the value of 30 kids each year getting their high school diplomas?”

Bicknell said he sees former Teen Center and Lighthouse Shelter attendees on the streets of Portland every day, but they’re almost never homeless any more.

“Only about 5 percent of our Teen Center kids move on to need adult homeless services,” he said. “When I see them out on the streets, they’ve grown up to get married, have families and jobs, and become productive members of society.”