Recording its highest roll in "living memory'' has prompted Tahuna Normal Intermediate to discuss school expansions and enrolment zones with the Ministry of Education.
Principal Tony Hunter said the school's roll had surged 9%, from 488 last year to 533 this year.
"We don't have any historical records that go a long way back, but as far as people's memories go around here, we've never had a roll this high before.''
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The roll has been steadily increasing from 374 in 1998, when the Otago Daily Times first started recording annual school rolls, and came close to 530 in 2004.
Mr Hunter said the school had capacity for about 540 pupils.
"I've been in discussions with the ministry about property matters, capacity and enrolment schemes.
"We've discussed putting more buildings on site. Certainly, we're near capacity at the moment.''
He believed the increase in intermediate pupil numbers was caused by a growing belief among parents that intermediate schooling was an attractive option for their children.
"All the intermediate schools are buoyant at the moment because of the opportunities that we provide for year 7 and 8 students.''
The increase might also have been caused by growth in Dunedin's primary sector, which was following through to intermediate level, Mr Hunter said.
The had also been an increase in the number of families migrating to Dunedin, he believed.
"Certainly, we have families that have moved to Dunedin, and their children are enrolling at our school from out of town.
"I guess it's simply because there's more people in Dunedin.''
Mr Hunter was delighted with the growth.
"It just means that we can offer more opportunities for students because we've got more specialist options for students to take part in, and more ministry funding.
"It's always positive to have a full roll.''
When asked if he thought the closure of the former Macandrew Intermediate in South Dunedin had an impact on his growing roll, he said he did not know, because there were still many full primary schools in the area that had year 7 and 8 classes.
"We're not getting into any of that sort of politics. We're just doing what we're doing.''
Dunedin North Intermediate principal Heidi Hayward said her roll had increased from 250 last year, to 262 this year.
"We're actually out of room. We are struggling. We've got people sharing rooms at the moment.''
There had been a consistent rise in pupil numbers during the past decade, and the increase was expected to continue, she said.
As a result, the school had also been liaising with the ministry about building more classrooms on site.
Balmacewen Intermediate principal Andrew Hunter said his school already had an enrolment zone in place, so the school could not grow any further.
"We've got 17 classrooms and they're all full. We're at capacity, and have been for the last seven or eight years.
"Our capacity is 490 to 500 pupils. Five hundred is uncomfortable for us. We're just below that this year, at 487.
"Unfortunately, some out-of-zone pupils have missed out this year because we are at capacity.''
Statistics New Zealand senior demographer Kim Dunstan said the latest population estimates indicated Dunedin city's population had grown by about 1100 people during the past couple of years, but the number of 11 to 13-year-olds (intermediate-aged pupils) had decreased.
He believed the increase in intermediate rolls could be explained by parents not sending their children to full primary schools or to secondary schools which enrol year 7 and 8 pupils.
"That might be the missing part of the jigsaw.''
Mr Dunstan said birth numbers in Dunedin went up between 2007 and 2012, so schools could expect increases in their rolls.
"Our projections suggest a fairly modest increase in the intermediate school ages over the next couple of years.''
