Brady Smith runs a small school, and he likes it that way. With fewer than 300 students enrolled, he can get to know everyone at the James Baldwin School in Chelsea.

But being small has its drawbacks, too. Smith shares a building with five other schools, which means every academic year begins with negotiations over who gets access to which stairwells, the cafeteria, the auditorium — and when. It’s hard to field a theater group with such a small roster. And since budgets are based on enrollment, money is short for much needed renovations in a building that he calls “literally old school.” (It went up in the 1930s.)

“Obviously the scale is both a positive and a challenge,” said Smith, who serves as the school’s principal but splits leadership responsibilities with a teacher. “There are economies of scale that could bring some really wonderful experiences into co-located buildings.”

Carmen Fariña, the outgoing schools chancellor, emphatically agrees and is taking a post-retirement role shepherding the Co-Located Campus Initiative — a two-year-old office that helps school leaders like Smith collaborate better on shared campuses. The education department says Fariña will serve as a volunteer advisor for the “passion project” after she steps down at the end of March — a move that her replacement, Richard Carranza, said he welcomes.

Like much of Fariña’s tenure, the initiative can be seen partly as a reaction to the policies of the previous mayor, Michael Bloomberg, who broke up large high schools across the city. The large schools were replaced with clusters of smaller schools within a single building.

While research has credited Bloomberg’s approach with boosting graduation rates, the small schools movement also created a new set of problems on many campuses. About 380 district schools are co-located throughout the city.

Shared space can lead to logistical hurdles and personality clashes, and the Department of Education has the Office of Campus Governance mediate disagreements about space-sharing and host training sessions on how school leaders can get along. The department even published a 122-page handbook laying out how colocated schools can work together. (A separate office handles relationships between charter schools and traditional schools that share buildings.)

“It can be a nightmare,” said one Bronx principal who shares a building with multiple schools and requested anonymity because he said he did not have permission to speak about his job. “It’s like a nine-dimensional puzzle.”

But Fariña’s initiative aims to move beyond the logistical and administrative headaches of space-sharing and focus on how schools can work together in the classroom. The goal is “collaboration in instructional practices, sharing of resources, and maintaining a safe and collegial campus where students and parents feel welcomed and appreciated,” the city’s handbook says.

Small schools can struggle to meet their students’ needs. With strained resources, some co-located schools can’t provide minimum required instruction time or math, social studies and science course offerings, according to a 2014 report by the Campaign for Educational Equity at Teachers College. Co-located high schools struggled to provide enough foreign language classes that allow students to earn an advanced Regents diploma — even though those classes are required by the state, the report found.

Nicole Manning has taught on co-located campuses for much of her career, including currently at the Business of Sports School, which shares a building in Hell’s Kitchen. She said she’s long noticed that arts programs are lacking at the schools, with few opportunities for drama, band, or vocational courses.

“I think the experience for the kids could be richer,” she said. “I don’t think that’s one person’s shortcoming. I think that’s a systems thing.”

Under Fariña’s leadership, the city has merged or closed some small schools. Now, through the initiative, Fariña wants to encourage schools to pool their budgets and staffs while still maintaining their size.

So far, 24 campuses across all the boroughs are involved, touching 138 schools and programs. In a signal of how important the work is to Fariña, Aimee Horowitz was tapped to lead the initiative — a move that raised eyebrows over the outgoing chancellor’s influence. Until now, Horowitz has led the mayor’s high-profile Renewal turnaround program.

“We work to improve the overall culture and climate across schools on campuses, and make sure resources are shared so teachers and kids can have access to more programs and opportunities,” Fariña wrote in a recent op-ed.

Fariña has zeroed in on campuses where she wants to push that work forward, meeting one-on-one with principals to kick it off. One of those campuses is the Bayard Rustin Educational Complex, where Smith’s school is located.

As part of the initiative, Smith said the education department is helping to pay for a welcome center for parents who visit the imposing building — a priority he said the chancellor has emphasized.

The Rustin Complex schools are already doing a host of other things laid out in the co-location initiative. A campus-wide group of parents meet regularly, recently diving into the contentious issue of whether metal detectors should be installed. Students come together in an afterschool club where young men create rap songs about their lives. Principals split the costs and for building-wide college trips which are chaperoned by staffers from each school.

“I think we all recognize that they’re all our students, even though there are six schools in one building,” Smith said.

Other issues are tougher to work out, especially when schools with diverging philosophies share the same building. Fariña has called for schools to open up their advanced courses campus-wide so more students have access to college-level work. But what if schools use different grading methods or testing practices to track student progress? Which principal should oversee that teacher’s work? And who, ultimately, should be held responsible for that student’s outcomes?

The same kinds of questions arise when it comes to implementing a campuswide approach to school discipline, or deciding what kind of training to offer all the teachers in the building — both laid out as initiative priorities — while also maintaining the characteristics that make each school unique.

“It’s exactly because of that, that we’ve chosen not to do more sharing,” the Bronx principal said.

Shino Tanikawa, a parent in Manhattan’s District 2 who served on a city working group dealing with school space, said she is generally opposed to co-locating schools. It creates extra work for administrators when they could be serving students, she said. But she also recognizes that it would be difficult to undo the legacy of small schools. Parents and students become attached to their schools. Some principals and teachers, even while acknowledging the difficulties, say they can build deeper relationships when there are fewer students to keep track of.

With that in mind, Tanikawa said the education department might as well help co-located schools grapple with the situation they’ve been dealt.

“They are not going away,” she wrote in an email. “Given that, I think it is good to focus on how to make it work.”