Mixed-Income Housing in Massachusetts is Significant Source of Affordable Rental Homes
Oct 05, 2026
By NLIHC Research Team
An Urban Institute report released in July, Can Mixed-Income Housing Advance Housing Supply, Affordability, and Opportunity?, found that mixed-income housing accounted for nearly 60% of large multifamily developments built between 2021 and 2025 in Massachusetts’ two largest metropolitan areas (Boston and Worcester). As a result, more than half (56%) of the 9,224 affordable homes produced in large multifamily developments during this time period are in mixed-income developments.
The authors defined mixed-income housing as a mix of market-rate and regulated affordable rents in large multifamily developments of 50 or more rental units. They further split these mixed-income developments into two categories: those where 20% or more of the units are rent-regulated and affordable, and those where less than 20% of the units are rent-regulated and affordable.
Mixed-income development has increased in Massachusetts in recent years. From 2021 to 2025, mixed-income housing accounted for 58% of new large developments and 65% of all new rental units in the Boston and Worcester-Springfield metro areas, a stark increase from the early 2010s when market-rate and fully affordable developments both outpaced mixed-income construction. At the same time, the average share of affordable units per development has decreased. Most mixed-income developments contain between 10% and 30% affordable units.
Mixed-income housing developments are, on average, larger than both market-rate and fully affordable developments, with a median of 172 units compared to 138 and 100 units, respectively. This is likely because locally implemented density bonuses (and larger developments in general) allow developers to at least partially subsidize the cost of affordable units with additional market-rate units, meaning less burden on the government to provide public subsidies for affordable units. In addition, larger-scale developments can better absorb the costs of the layered financing required to produce affordable housing.
A benefit of mixed-income housing is the provision of affordable rental units in higher-income neighborhoods, helping to decentralize poverty and give lower-income families access to higher-quality public services such as schools, hospitals, and recreational centers. The average median neighborhood income of mixed-income developments is $110,135, compared to $74,894 for fully affordable housing. Families in mixed-income neighborhoods also may see an increase in economic mobility, with children seeing better educational and career outcomes compared to children in neighborhoods with concentrated poverty.
Massachusetts has a few advantages that allow mixed-income developments to thrive:
- Chapter 40B requires municipalities to have at least 10% of their housing stock designated as affordable housing. In municipalities where this threshold is not reached and without a certified housing plan, developers can bypass zoning restrictions if their developments contain a minimum share of affordable units (25% affordable for households with incomes below 80% of area median income (AMI) or 20% affordable for households with incomes below 50% of AMI). Since 1990, 40B has directly incentivized mixed-income developments by counting all units (both market-rate and affordable) in mixed-income developments toward the 10% municipality guideline as long as those developments have the required share of affordable units.
In the early 2000s, “inclusionary zoning” (IZ) began spreading across localities. Generally, developers in areas with IZ are required or incentivized to designate a percentage of units as affordable in new developments.
Massachusetts has high market demand, which allows mixed-income housing to be profitable for developers with minimal government subsidies. In a state with lower market demand, developers would find it more difficult to subsidize affordable rents with market-rate rents.
The report is available.