The State of Massachusetts has several resources for homeowners who are looking to hire a contractor. Links to some of these resources can be found below.
Homeowners Guide to HIC: https://www.youtube.com/watch?v=Qyge0D0XCk4
Home Improvement Contractor Database: https://services.oca.state.ma.us/hic/licenseelist.aspx
Homeowner's guide to hiring a home improvement contractor: https://www.mass.gov/info-details/homeowners-guide-to-hiring-a-home-improvement-contractor
Understand a Home Improvement Contract: https://www.youtube.com/watch?v=XWVvypemLL8
Construction Supervisor License (CSL) Verification: http://elicense.chs.state.ma.us/Verification/Search.aspx