Spencer Booker lives in Aquinnah, and when it came time to decide where to send his three children for grade school, the choice was obvious. Proximity was key, so they chose the Chilmark School.

"It was geographical, the closest school to my house," he said. "And it's a great little school, very intimate, very supportive. All the teachers know all the students, first name and last. That's the kind of environment I want to put my kids into for their education."

The Chilmark School is small indeed - 45 students in the K-5 facility at Beetlebung Corner. Mr. Booker's three kids all go there.

But what makes the school good for the Booker children also makes it a prime target for another group of people with a different set of concerns - money.

Running this little school in Chilmark isn't cheap, with per-pupil costs topping the $20,000 mark. This Thursday, the financial and educational viability of the school will be one of the main topics at two back-to-back meetings.

It's a critical juncture, and if you spent any time talking to people in and around Chilmark this week, you could hear some of the worry in people's voices.

The first meeting starts at 5 p.m. at the West Tisbury School when the Up-Island Regional School Committee will sit down with the West Tisbury finance committee and hear whether it might be cheaper for the Up-Island school district to shut down the Chilmark School.

The finance committee in West Tisbury is backing a proposal at the annual town meeting in April asking voters to take the first step to leave the regional school district. The board believes that West Tisbury taxpayers are shouldering an unfair portion of the educational costs in the district, which includes Aquinnah, Chilmark and West Tisbury.

While the two boards analyze the financial scenarios, a second meeting is scheduled for 7 p.m. at the Chilmark School. The goal will be to form a task force from the school community and charge it with producing something of an internal report card - what's working and what isn't at the Chilmark School.

"We want a task force to generate ideas," said Susan Parker, the Chilmark representative on the Up-Island Regional School committee. "What do you like about the Chilmark School, what do you want to preserve and what areas do you want to see changed?"

One thing is certain. With the talk of secession getting louder in West Tisbury, the political will in Chilmark to defend its school is gaining strength.

Ms. Parker helped put that political mood in some context. "Many people believe this is part of the heartbeat of the community. I don't think people want to see Chilmark become simply a retirement community," she said.

Lois Mayhew, the mother of a second grader who has sent three other children to the Chilmark School, picked up that same theme. The Chilmark School is a main ingredient in keeping this town vital, she said.

"It would be a very different town without that school," she added. "It's right there by the post office and the library, the only shows in town in the winter. It helps knit the community together. If you want to keep that identity in the winter, you need the school." Last week, Chilmark selectman Warren Doty said that closing the school is not an acceptable option to town leaders.

In some respects, the Chilmark School is accustomed to weathering tough times. The building has seen a succession of principals, five in the last 12 years. Staff turnover has also been a problem. The school has just three multi-aged classrooms, but has hired five replacement teachers in the last six years.

And the new $3.6 million school building - which opened just four years ago - has been a maintenance headache from the start with mold under the floor, a leaking bell tower and rotting exterior doors just some of the problems that needed fixing.

Enrollment has been another problem. The school was built to hold 100 students. Last year, 59 students attended. This year, that number fell to 45, and principal Carlos Colley blamed the high cost of housing in town.

But that's only part of the conundrum. School choice means parents up-Island can send their kids anywhere on the Island and particularly to West Tisbury, home to both the West Tisbury School and the Martha's Vineyard Public Charter School, both of which provide a K-5 program.

Throughout the up-Island district, enrollment is falling. The West Tisbury School has seen its numbers drop three years in a row. But in Chilmark, even a little dip in the enrollment can hit hard, drastically affecting the per-pupil costs. High per-pupil costs also drive up the reimbursement rates that the up-Island district pays when its students opt for the charter school.

Mr. Booker is, in fact, something of a rarity in the school choice scenario. His three children make up almost half of the eight Aquinnah kids who attend the Chilmark School. Most of the elementary-aged children from Aquinnah - 12 of them - make the long commute to the West Tisbury School. One attends the charter school.

The Aquinnah factor has a history. Back in the seventies and eighties, there wasn't room for Aquinnah children at the old Chilmark School, which had just two rooms before a trailer was added for a third classroom.

School choice also means that kids from Chilmark can opt not to attend their own community school. This year, 21 kids from Chilmark in the K-5 age bracket are doing just that: 14 are at the West Tisbury School and another seven are at the charter school.

So, clearly, one question facing the task force that forms this Thursday will be understanding why parents are making these choices, some of which mean driving their children right past the Chilmark School. Ms. Parker said the keywords guiding this new committee will be "vital and viable."

The parents and leaders backing the Chilmark School would like to see it remain part of the up-Island region which was formed in 1993. Back then and up until last year, much of the rationale behind the regional school district was financial. Simply put, the region worked like a magnet for state educational funding.

But as the state budget crisis unfolded, the dollars from Boston began drying up.

Now, some people up-Island are looking at other reasons to keep their educational alliance from falling apart.

"We have all kind of potential here," said Roxane Ackerman, Aquinnah representative to the up-Island school committee. "We have to look at our educational issues together instead of separating."

Ms. Mayhew, who served on the Chilmark school committee more than 10 years ago, said the three up-Island towns have collaborated for years on meeting educational needs. "We have a history of working together," she said.

She doesn't blame West Tisbury for raising financial concerns, but she is not ready to sacrifice a unique school in Chilmark over money.

Mr. Booker feels much the same way. "The school is brand new," he said. "For them to close it down now seems to me a larger waste of money."