In the 1880s, as Chicago’s population was more than doubling and immigrant workers lived under slum-like conditions, the city’s streets teemed with homeless boys whose families could not support them.

Chicago Archbishop Patrick Feehan wanted to do something to help, and asked Father Louis Campbell to create a home for working boys. Campbell found temporary quarters above a Catholic library on LaSalle Street, in the shadows of the Board of Trade building, and started St. Paul’s Home for Working Boys in 1887. What would become Mercy Home was born.

“These were kids who had come to Chicago looking for work, and they (the archbishop and the priests) were concerned that they would get into trouble and some bad situations if they didn’t have a place to go with the structure they needed,” said Mark Schmeltzer, Mercy Home’s director of communications.

Now celebrating its 125th anniversary, Mercy Home has helped about 25,000 children. Those it helps today might come from different situations, but they need the same things.

“The kids need to be loved, they need a home, they need safety,” Schmeltzer said. “They need a structure that allows them to fall and get back up.”

Providing that is “the work of the Gospel,” said Father L. Scott Donahue, Mercy Home’s president since 2006.

“It’s God’s mercy that’s provided to the children that are entrusted to our care, and to the extended families we care for,” said Donahue. “The conviction comes from the Gospel. Jesus was always spending time with those who were experiencing suffering, those who were marginalized, those who were poor, those who had no hope. Jesus had great compassion for children.”

He went on to cite Matthew Chapter 25, when Jesus enjoined his followers to feed the hungry, give drink to the thirsty, clothe the naked and shelter the homeless.

Mercy Home, headquartered since 1889 at 1140 W. Jackson Blvd., provides all that and more to about 135 teenaged boys and girls, who have resided on their own campus in the Beverly neighborhood since 1987. It also helps about 100 children through its FriendsFirst mentoring program and provides support to about 250 adult alumni who ask for it each year. Many other young people who reach out for help are assisted with referrals to organizations that can better meet their needs.

That’s because Mercy Home is just that — a home. It does not take guardianship of the children who live there; their parents, other family members or other guardians retain that. It is not a school; the young people attend 52 different schools, many of them Catholic schools, throughout Chicago. It is not a detention facility; young people are free to leave and will not succeed if they do not want to be there. Young people not only go to school; they can participate in school sports programs and other extracurriculars or have afterschool or summer jobs.

Rather, it is a place where children who need to get out of a chaotic home environment can come for safety and security. Their physical needs, for food, shelter and clothing are cared for, they are educated and they receive emotional support through group and individual therapy and spiritual support through prayer, encouragement to participate in their own faith traditions and a requirement that they all participate in community service projects.

Children each are assigned to one of 14 homes within a home, and each child has an adult advocate to make sure they are getting what they need. Advocates each have no more than two children.

All of that takes money, and Mercy Home raises about 99.8 percent of its $30 million budget privately.

The young people often have suffered some kind of trauma or abuse, often at the hands of family members. They might come from unsafe neighborhoods where they are targeted by gangs, or have parents who are so consumed by their addiction to drugs or alcohol that they have nothing left to give their children. They are referred by guidance counselors and teachers, by priests and pastors, by police and family members and friends. Sometimes they show up on the doorstep on their own.

Most are behind grade level when they arrive, and students work with tutors five evenings a week to catch up. Last year, each high school senior graduated. This year, the home is working on renovating a 16-unit apartment building in South Shore that will help Mercy Home alumni transition to completely independent living.

Donahue said Mercy Home’s coworkers — he doesn’t call them staff, because they are all coworkers in the mission — are taught when they come on board about the history and mission of Mercy Home, and the importance of attending to the children’s spiritual development. As many of the children as possible attend Catholic schools — Mercy Home pays their tuition — and children can be trained and serve at the altar for the televised Masses from Mercy Home. Scripture study is available at both the boys’ and girls’ campuses, and prayers are said before meals.

All the young people are encouraged to go on retreats to reflect on the role of God in their lives, and all of them are asked to reflect on the community service projects they do.

“They really come from difficult beginnings,” Donahue said. “They’ve experienced a lot of trauma. But once they get here, their physical needs are met, we try to meet their emotional and spiritual needs. In a sense, a lot has been given to these young people. Helping other people really gives them a basis for understanding the Gospel, for understanding why Jesus did what he did, why our coworkers do what they do, why I do what I do.”