MassLegalHelp is a great resource to educate and support people who are searching for housing, facing foreclosure or eviction, or are experiencing homelessness. Other resources on their site include tenants rights, housing discrimination, and checklists for tenants before a move-in.
Community Legal Aid provides free civil legal services to low-income and elderly residents Central and Western Massachusetts and the Mass Fair Housing Center is oldest fair housing center in Massachusetts. They offer free legal services and accept housing discrimination complaints from protected classes of people.
A by topic list of laws in Massachusetts regarding renters, homeowners, foreclosures, evictions, and many other topics can be viewed on the Mass.gov website.