Expanding the 100% Affordable Housing Overlay

“[Affordable housing] would mean the world to my family. We can have stability. We would have our own space instead of sharing a room.

More than 21,000 people are waiting for a home they can afford in Cambridge, but the city still isn’t building enough.

In October 2020, the City Council adopted a 100% Affordable Housing Zoning Overlay, removing certain barriers to the production of affordable housing. It has helped, but not enough - the city is still falling significantly short of its goals and our needs.

Now, in 2023, four City Councillors have proposed amendments to the AHO. These amendments would expand and strengthen the AHO by making more sites across the city available for affordable housing, and increasing the allowed density of affordable housing on those sites. However, the package has been met with strong opposition from “not in my back-yard” voices. The City Council needs to hear your support.

Please join us in demanding more affordable housing in Cambridge. Sign and share our petition, email City Council, and see "How can I help?" below for more ways you can help.

Have further questions? Email [email protected]


Cambridge’s population has grown much faster than its supply of housing, especially affordable housing. 

The primary culprit? Our zoning laws – layers of inequitable restrictions, accumulated over decades, which severely limit where housing can be built in our city. This has caused our housing supply to fall ever further behind our growing needs and has caused rents to skyrocket. Since 1980, we have added over 45,000 jobs, but only 13,000 homes

The Cambridge housing market has become a cruel game of musical chairs, with those least able to afford rent getting pushed out.

Federal and state governments consider a home “affordable” when it costs no more than 30% of a household’s income to live in it. “Affordable housing” refers to housing which is income-restricted (i.e. you must meet certain income eligibility rules to live in it) and offered at below-market-rate rents or prices. It is an umbrella term which can include public housing, supportive housing, ownership housing, or rental housing.

(Some examples of affordable housing in Cambridge: Frost Terrace in Porter Square, the Manning Apartments in Central Square, the Trolley Square Apartments in North Cambridge)

Affordable housing units are created in a few different ways, but the two main ways in Cambridge are:

  1. Inclusionary Zoning (a requirement that new large housing developments must offer 20% of their units as affordable housing)
  2. 100% Affordable Housing buildings built by non-profits or by the Cambridge Housing Authority using city (Affordable Housing Trust), state, and federal funds. These are the kind facilitated by the AHO.

Each funding source for affordable housing comes with different requirements and restrictions. See here for more information on the income restrictions for different kinds of affordable housing. Most “deeply affordable housing” (housing affordable to those making 30% of the federally-defined Area Median Income) is provided by the Cambridge Housing Authority, often using vouchers in tandem with below-market-rate housing units.

Building affordable housing has become increasingly difficult over the past 50 years as federal funds have diminished, land costs have increased, and zoning has become more restrictive. In 2019, A Better Cambridge hosted a talk, “Introduction to Affordable Housing Finance”; slides and video are available.

While Massachusetts has a “Chapter 40B” law which in theory allows affordable housing developers to apply for relief from restrictive zoning, there is no guarantee of success, and the uncertainty involved in Chapter 40B makes it extremely difficult to line up financing from federal and state agencies. This was a large part of the impetus for the original 100% Affordable Housing Overlay, which provides a predictable, as-of-right permitting process.

The high demand for housing in and around Cambridge has run smack into the many zoning laws – enacted over decades – that limit where apartments or condos can be built. The resulting severe shortage of housing has led to sharply rising rents and home prices and the near-disappearance of “starter homes” for renter households trying to join the minority (35%) of Cambridge residents who are homeowners. 

City Councilors have received desperate phone calls from parents concerned about having to move their children out of Cambridge schools mid-year, and from elderly long-time residents who can’t find another home in the city, because of rent increases. The Cambridge Housing Authority’s waiting list for affordable apartments includes over 21,000 people.

Building affordable housing requires cobbling together financing from many sources which were hard to qualify for under our pre-AHO zoning laws and permitting procedures. The AHO was designed to allow more housing on eligible lots – reducing the cost per unit – and to remove barriers in the permitting process – so housing plans would be more likely to qualify for the necessary funding.

In its first two-plus years, the AHO has enabled six developments in six neighborhoods, which include about 280 new homes plus 212 to be entirely or substantially rebuilt. (In addition, the Walden Square proposal would add another 103 homes – however, that proposal has stalled, possibly permanently.) Cumulatively, these sites will include housing for the formerly unhoused (with on-site services), replacement for structurally unusable apartments in public housing, more large apartments for families and will put historic but unused buildings to productive use. The Planning Board has held hearings, taken public comment, and applied the City’s Affordable Housing Overlay Design Guidelines in giving input on all of these proposals.

AHO Projects by Neighborhood


ready by

new units


units @ % median income

52 New St

Cambridge Highlands




14 @ <30%; 83 @ 30-60%; 10 @ 61-100%

Jefferson Park Federal

North Cambridge



and 175 to be rebuilt

278 @ <80%

Walden Square II

Neighborhood 9



Inactive; status unclear

all @ <80%

Sacred Heart Church

East Cambridge




8 @ <30%, 2 @ <50%, 30 @ <60%, 6 @ <80%

116 Norfolk Street




and 37 to be renovated

62 @ <80%

1627 Massachusetts Ave





not announced

Data from Cambridge Community Development Dept, as of 2 Feb 2023

Ironically, opponents of the original 100% affordable housing overlay have claimed that these early results show  we don’t need to make any changes to the AHO. But as described below, these numbers fall well short of the rate needed to ever meet our need for affordable housing. In addition, many of these projects represent the easiest opportunities to get off the ground, and this current pace is likely to slow without further amendments to the overlay.

Even with the AHO now in place, Cambridge is running far behind its Envision Cambridge goal of building 3,175 new affordable units between 2018 and 2030, let alone providing enough housing for the 21,000-person CHA waitlist. According to the Cambridge Development Log, from 2019 to 2021 we averaged only 122 affordable homes - including both new and renovated homes - per year. Some reasons this is happening:

  • Only two of the six proposals seeking an AHO permit have received one so far, with 1.5-3 years until completion. Planning time is long – design, community meetings, city department and Planning Board meetings and financing can take 2-3 years – and construction takes a couple more. We need to have much more new housing in the pipeline to adequately house even our current number of low-income households.
  • Currently, the AHO only allows a small number of sites to reach density levels high enough to be cost-effective for affordable housing. Even 2072 Mass Ave, which had the support of 7 City Councillors, failed because zoning was too restrictive.
  • The Affordable Housing Trust has looked into buying a number of sites recently, but without assurances of higher density they failed to make competitive bids for many. Most AHO developments have been on sites that were already in non-profit hands.

Expanding the AHO means Cambridge can uphold its progressive values, it can maintain its diversity, and it can welcome refugees–including future climate refugees. It means children born in Cambridge have a chance to live here, and not only by living with their parents. It means children can maintain bonds with their classmates in Cambridge public schools. It means those in need of affordable housing are not exposed to the constant whims of the housing market, unscrupulous landlords, overcrowding, building code violations, and lack of heat on cold winter days. It means our school teachers and staff do not have to commute several hours to work in our public schools.

CHA has collected Stories of the Can’t Wait List from some of the people waiting for affordable housing in Cambridge. When asked what affordable housing would mean to them, those on the CHA wait list said: 

“Affordable for me is not having to choose between food and a roof over my head.” 

“It means a home and food on the table.” 

“Working just one job and being able to be more present in my children’s lives.” 

“I would be able to send my son to a great school. I would also be able to continue living in the city that my family has lived in for over a century.”

“It would mean the world to my family. We can have stability. We would have our own space instead of sharing a room. We would have a home.”

“I would be able to provide my daughter with a loving home. Give her the childhood I experienced in Cambridge.”

“It is life itself. I cannot hold up my family and it is killing me. There is no way forward for me.”

The amendments proposed by four Councilors would expand and strengthen the AHO by making more sites in every neighborhood of the city available for affordable housing, and increasing the number of affordable homes that could be built on those sites. Specifically, they would allow:

  • More affordable housing in all parts of Cambridge – specifically, the amendments allow up to 13 stories of affordable housing along “AHO corridors,” a set of listed streets spanning the city, including Mass Ave, Mem Drive, Cambridge St., Mt. Auburn St, and others. This would allow affordable housing proposals like 2072 Mass Ave to succeed, and would ensure that every neighborhood of the city has sites where affordable housing can be built at sufficient scale to be financially viable.
  • Taller buildings in "AHO squares" – specifically, up to 25 stories of affordable housing in Central, Harvard and Porter Squares as well as the "Webster Square" auto-shop area near the new Union Square T station. This would allow significantly more transit-oriented affordable housing like the Manning Apartments.
  • Greater flexibility for open space. AHO proposals that provide more-than-required open space would be allowed to take their sacrificed building bulk and put it into increased height. This provision would have allowed more housing for the formerly homeless to be built at 116 Norfolk St, and could have improved the site plan of Jefferson Park.

Map showing envisioned “AHO corridors” (solid black lines) and “AHO squares” (shaded areas).

The amendments were introduced at the Cambridge City Council in November 2022, and sent to the Housing Committee. In order for these amendments to pass, they must be reported out of the Housing Committee to the full City Council, then go through the full zoning amendment process by being sent to the Planning Board and the Ordinance Committee, then back to the full City Council for two final votes. Each stage of the process is a public hearing. The whole process could take anywhere from three months to years.


Only a small percentage of lots undergo reconstruction or major renovation each year; zoning changes leave the rest alone. This is especially true in affordable housing development, where there are only a small number of developers willing and able to build in Cambridge. Expanding the AHO is one way to ensure that every acquired site can be developed to its fullest potential; however, Cambridge also needs to fund its Affordable Housing Trust more substantially and predictably to increase the number of site acquisitions.

A bigger housing crisis – particularly for the most vulnerable. 

Every year, new buyers enter the Cambridge housing market, each one bidding rents and property values up a little bit more. With every new buyer, Cambridge gets a bit more expensive. That’s how apartments in century-old three-deckers became luxury housing, and small structures, built as workers’ cottages, became out of reach for most workers – bit by bit.

As Cambridge housing becomes affordable to fewer and fewer households, the character of the city will also change – economically, socially, and racially. Without more affordable housing, we will continue to lose our diversity, more residents will be displaced, and more residents will become homeless.

New multifamily housing is environmentally friendly. Shared walls reduce energy use, and modern buildings use less energy. Building housing in Cambridge is especially environmentally friendly, because it reduces sprawling exurban housing development, and Cambridge residents have much lower carbon footprints than suburban residents (for instance, they are less likely to drive and more likely to use public transit). This is even more true of residents of affordable housing.

  • Sign and share the petition to support expanding the Affordable Housing Overlay.
  • Share your views about our housing crisis and these amendments with the City Council.
    • The number of emails Council receives really matters, so please encourage your friends to send something too – even if it’s just “Please expand the Affordable Housing Overlay”!
    • Emails can be short, but feel free to include your personal housing experiences and priorities for extra impact.
  • Add yourself to the ABC email list so you’ll know the most effective times to write to the Council.
  • Read and share Stories of the Can’t Wait List, about some of the 21,000 people waiting for affordable housing in Cambridge.