In the afterword to her new book Catholic Girl, which documents teenagers at Catholic girls’ schools in New York and New Haven in the mid-1980s, the photographer Andrea Modica likens the experience of initiating the project to a first kiss. “You’re mad about the subject,” she says, “and there’s something about the first time it happens that is slightly out of control and magical and addictive.”

Today Modica is a professor of photography with a career spanning four decades – she’s known for her luminous black-and-white portraiture using large-format cameras and platinum printing – but back then, in her second year of graduate studies at Yale’s school of art, she was struggling to find her voice. “All those months of trying were [leading to] the most dreadful pictures,” she recalls over Zoom from Philadelphia, where she lives and works. “They were well put together, the form was there, but the necessity, the connection with the subject, was not.”

On a snowy day in March 1984, on a visit home to Bay Ridge, Brooklyn, she dropped by her old high school to meet her beloved art teacher Len Bellinger and asked on a whim if she could photograph some of his students. “I didn’t assume I’d be able to, but he let a couple of girls out of class and I took some pictures.”

Immediately she knew she was on to something. Despite the fact that the girls were all wearing the same uniforms, their personalities radiated out of the frame, as did their fashion sensibilities.

“It’s at the confluence of disco and punk,” Modica recalls of the era. “Bay Ridge was where Saturday Night Fever was filmed when I was in high school, so disco was very important in that neighbourhood – and seven years later it’s still hanging on.” She points to one girl who stands by a wall with her hands clasped below the waist, rolling on her ankles. “She still has the Farrah Fawcett haircut. She’s got an ankle bracelet on a chain around her neck, which is a symbol that she has a boyfriend. She has her skirt rolled up so that she’s showing her legs.”

Other girls project a more in-your-face punk attitude. Black eyeliner abounds, as do leather jackets, piercings and quiffs. “They look tough, but also a little quaint,” says Modica. One girl is photographed during her school’s no-uniform day and she’s making the most of it, but, as Modica points out, “she’s wearing not one, not two, but three religious medals. So despite this wild makeup and hair, there’s still this sense of a comfort zone – a need to have something religious on when going to school.”

As much as Modica regards the series 40 years on as a “little time capsule of music and fashion”, religion is also a key element, albeit less visible. What were the punk fashion gestures reacting against if not the conformities of a Catholic upbringing? According to Modica, however, her high school was unusually liberal. “We had young radical nuns teaching us. In religion classes they’d say: ‘We don’t believe in abortion or premarital sex [but] what do you think?’ We were given a voice and required to support what we thought.”

That openness is evident in her subjects, who clamoured to be photographed after she took the initial portraits in March 1984. “I don’t know if some girls came because it meant they could get out of class for 10 minutes, or if it was just a curiosity, but nobody did it begrudgingly.” Modica was shooting with an 8x10 large-format camera, which meant the portraits took longer, and because of that “one might argue there’s a certain amount of collaboration involved”, she says. Some girls would tweak their poses. Often, friends on the sidelines would end up inside the frame.

Although Modica didn’t publish the series at the time, she describes it as a catalyst for future projects, including one called l’Amico del’Cuore, exploring the dynamics between best friends. Her fascination with uniforms continued in her 1993 monograph Minor League, portraying New York baseball players. “They were really proud of the uniforms,” she says. “They had much stricter rules about them than the girls.”

When Modica dug out the high school photos during lockdown and decided to turn them into a book, she was amazed to find that, four decades later, many of the girls she contacted still had the prints she’d sent them at the time. Getting back in touch has been “spectacularly fun”, she says. “One woman came to a signing I was doing, and oh my goodness. In the photograph from 40 years [above, wearing glasses] ago she’s very shy and conservative, but now she’s blossomed into this vivacious woman, an art teacher. It was a blast.”

As a teacher herself, Modica has learned to step aside whenever she sees her photography students becoming captivated by a subject – their own artistic first kisses. “The first time it happens for somebody is unlike any time thereafter,” she says. “Maybe the technique is not as good as it’s going to be in 10 years, but the subject, whatever’s driving them, makes the technique happen, not the other way around.”

That cold spring day in 1984 was when it happened to Modica and those girls with their big hairstyles and leather jackets, teetering on the brink of adulthood, have influenced her work ever since.

• Catholic Girl is published by L’Artiere