When Andres Ortiz first enrolled at Cristo Rey Jesuit High School in Chicago, his English was limited and he had not given much thought to his future.

By the time he was turning his tassel and tossing his cap in the air as a member of the school’s first graduating class in 1998, he was fluent in English and set to attend Lewis University, a Lasallian university in Romeoville, Ill., to study business administration.

“At that crucial time when you are a teenager, you’re trying to figure out who you are and where you want to go in life…. Cristo Rey was that place where I understood the path,” said Mr. Ortiz, who now works in a corporate capacity for Hyatt Hotels.

That transformation is the promise Cristo Rey offered when it first opened its doors in Chicago 30 years ago. It is a promise that has dramatically expanded since then: 40 more schools have opened as part of the Cristo Rey network since, the most recent of which enrolled its first class in Orlando, Fla., just last summer.

Mr. Ortiz remembers the efforts and initiatives of Cristo Rey’s first leaders 30 years ago, like John P. Foley, S.J., the school’s founder and first president. “He had a vision,” Mr. Ortiz said of Father Foley. “And look at where things are now.”

Mr. Ortiz will be joining other members of that original Cristo Rey class on Sept. 19, when Cristo Rey welcomes back its alumni for a celebration of its 30th anniversary.

Cristo Rey began in Chicago in 1996, when Jesuits of what is now the Midwest Province opened the first high school in an effort to expand their ministry to Chicago’s Southwest side and meet the needs of bilingual immigrant families in the area.

To assure that the program would remain affordable and sustainable, Cristo Rey Chicago pioneered the corporate work-study model: Students work one day a week in a corporate or nonprofit office setting, gaining professional experience while earning a significant portion of their own tuition. Classroom instruction on the other days of the week is extended to make up for the once-a-week work assignment.

According to the school website, the work experience and “accompanying career exploration, mentoring, and networking provides students with social capital and a significant advantage as they enter college and the workforce.”

The curriculum, too, is designed to meet students where they are. All students complete a dual-language course load rooted in the liberal arts, with 30 percent of coursework taught in Spanish. The school offers honors and Advanced Placement courses, with 93 percent of students passing at least one A.P. exam.

In an effort to meet the specific needs of the low-income families Cristo Rey Chicago serves, its students are shepherded through socio-emotional counseling and college prep services as well. 

Like Mr. Ortiz, Maria E. Luevano-Salazar knew minimal English when she enrolled at Cristo Rey as a freshman. A newly arrived immigrant and the eighth of nine children, she said Cristo Rey was an almost inconceivably perfect opportunity: it was safe, it was affordable and it would help her navigate high school while learning English.

“I knew some of my classmates from my elementary school that had different experiences in different high schools, and I think I was very lucky to have the type of support that I had—not only when I was a student here but beyond that,” Ms. Luevano-Salazar said.

She became comfortable speaking English and gained real-world work experience in banks and law firms. By the time she graduated in 2001, she earned a full ride to Loyola University Chicago. 

“I don’t think that I believed college was an option for me,” she remembered. But Cristo Rey  “provided opportunities that were beyond my own realm of possibilities,” Ms. Luevano-Salazar said.

Her career took her through jobs in government, education and the Archdiocese of Chicago before she eventually returned to Cristo Rey Chicago, where she serves as the vice president of mission.

But beyond the opportunities for upward mobility that Cristo Rey provides, it also offers the trademark spiritual development of a Jesuit education.

Mr. Ortiz grew up Catholic, but talking with the Jesuit faculty at Cristo Rey was the first time he had been asked to grapple with how religion could play a role in his life. This was such a profoundly moving experience, he said, that for a time, he considered becoming a Jesuit himself.

While that did not turn out to be the path for him, is grateful for the spiritual foundation that, even decades later, informs his approach to the world.

Shortly after Mr. Ortiz graduated in 1999, a $12 million donation from the Cassin Educational Initiative Foundation helped kickstart the Cristo Rey Network to replicate the Chicago high school model in other U.S. cities.

Cristo Rey grew quickly from this pilot project in Southwest Chicago into a network of high schools offering life-changing educational opportunities to students across the country. But for some of its earliest graduates, this is also not a surprising thing—the bones of an effective, altruistic and promising program were there from the start.

As she helps prepare for the weekend’s festivities, Ms. Luevano-Salazar said she is looking forward to taking time to appreciate the work of the school’s continuing mission.

“Thirty years later, and we are serving the community. We’re still responding to need and really transforming lives. It’ll be exciting to celebrate this weekend what has been done and what continues to be done.”

Will Martino is a Joseph A. O’Hare, S.J., fellow at America Media.