Brookline is once again facing the full force of Massachusetts’ Chapter 40B affordable housing law. For the first time since early 2022, the town’s percentage of affordable housing has slipped below the state’s 10% threshold. That seemingly small change is already triggering a cascade of new development proposals, neighborhood disputes, and high-stakes decisions for Brookline’s future.
What is Chapter 40B?
Chapter 40B allows developers to override local zoning if a town has less than 10% affordable housing. In exchange, they must reserve 20–25% of units at affordable rents. It has produced the majority of affordable housing in Massachusetts suburbs since its creation in 1969.
The 10% Line and Why It Matters
Under Chapter 40B, if a community has less than 10% of its housing stock classified as affordable, developers gain the right to sidestep many local zoning restrictions. As long as they dedicate 20–25% of units to affordability, they can appeal directly to the state if the town resists.
Brookline’s current shortfall is small—just a few dozen units out of nearly 28,000—but the implications are outsized. Planning Director Kara Brewton recently warned that as many as six new 40B applications could land this fall. For developers, this is an open window. For the town, it’s a loss of leverage just as housing pressures mount across Greater Boston.
Coolidge Corner: Harvard Street’s Revival
Nowhere is the threshold effect clearer than at 429 Harvard Street, the shuttered Citizens Bank site in Coolidge Corner. Developer Oak Hill Properties originally filed a 40B plan for a six-story, 40-unit building in 2023, complete with ground-floor retail and 20% affordable units. When Brookline regained temporary safe harbor above 10%, the developer pulled back.
This summer, with the town again below the line, Oak Hill returned with the same proposal. The Select Board has held a hearing and is preparing comments for the state housing agency. Whether residents like it or not, the project is moving forward under 40B rules, which limit the town’s ability to block or substantially scale it down.
For Brookline, the project is a reminder that even small dips under the 10% mark can change the development calculus overnight.
Chestnut Hill: A Permit, a Lawsuit, and a Waiting Game
In South Brookline, a 103-unit 40B project at Heath, Sheafe, and Hammond Streets illustrates both the power and the volatility of the law. The Zoning Board of Appeals approved the development this July after a lengthy review. But just weeks later, a neighbor filed a lawsuit in Superior Court to stop it.
The complaint raises environmental concerns—pointing to the dry-cleaning business currently on-site as a possible source of contamination—as well as quality-of-life issues. The abutter argues the six-story building would dwarf nearby homes and block sunlight. The developer insists the project is safe and needed, but the case is now in the courts, creating yet another layer of delay.
The episode shows how 40B can cut through local zoning hurdles but doesn’t eliminate conflict. In Brookline, it often just relocates the fight—from town hall hearing rooms to legal briefs and courtrooms.
Route 9: Commercial Promise vs. Residential Pressure
Perhaps the most consequential site is at 1280–1330 Boylston Street along Route 9. City Realty has been negotiating with Brookline on a plan for a commercial-heavy mixed-use development, including a hotel. Officials support the idea because commercial property generates far higher tax revenue than residential units—millions per year that could ease pressure on local taxpayers.
But the rezoning needed to make that plan possible has been delayed, most recently pushed off until 2026. In the meantime, City Realty announced it has filed preliminary paperwork for a 40B residential project instead: four buildings, hundreds of apartments, including towers up to 12 stories.
“Our strong preference is for a successful zoning overlay and a mixed-use development,” said Cliff Kensington of City Realty. “But as long as the opportunity remains, we will continue pursuing this [40B] application.”
It’s a strategic move. By preparing a 40B, the developer is signaling that if the town can’t act quickly, it will pivot from a tax-rich commercial plan to a state-backed housing project. For Brookline, the stakes couldn’t be clearer: act, or lose control over one of the most valuable parcels left on Route 9.
A Town on Edge
Brookline has long relied on 40B to deliver affordable units—dozens of projects over the years have helped the town get close to the 10% mark. But the process has never been smooth. Residents worry about traffic, scale, and neighborhood character, while officials balance the urgent need for more housing with the desire to keep growth under local control.
Now, with 40B back in play, the pressure is rising. In Coolidge Corner, a tall apartment block may soon rise where a bank once stood. In Chestnut Hill, a judge may determine the fate of a major new development. And on Route 9, Brookline could either secure its largest commercial project in decades—or see the site transformed by state override into a massive residential complex.
For a town that prides itself on careful planning, the coming months will test just how much control Brookline can hold onto. Until the 10% threshold is secured for good, the future of development here may rest less with local boards and more with developers and the state.
