This new law (Section 3A of MGL c. 40A) requires that an MBTA community shall have at least one zoning district of reasonable size in which multi-family housing is permitted as of right and meets other criteria set forth in the statute:

Minimum gross density of 15 units per acre

Located not more than 0.5 miles from a commuter rail station, subway station, ferry terminal or bus station, if applicable

No age restrictions and suitable for families with children

Department of Housing & Community Development's (DHCD) webpage on MBTA Communities: https://www.mass.gov/info-details/multi-family-zoning-requirement-for-mbta-communities