I am a Massachusetts resident. You can possess any knife but not carry in public any autos, ballistic knives, daggers, stilettos or dirks, which means any double-edge knife. This feature of the law protects collectors, but it does not specify how a collector is to legally carry his/her new purchase to their home, since public carry is a felony. Boston, Lawrence, Cambridge, Revere, Lynn, Salem and Beverly have 2.5" blade limit for knives carried in public. These are local ordinances, punishable by arrest and $300 fine. Worcester also has a blade limit, 3" if I recall correctly. Holders of a Massachusetts Class A licenses to carry firearms (even if restricted to hunting and target shooting) are exempt. For what its worth, I EDC a 4" lock-blade folder at all times. I simply removed the clip and carry it completely concealed. I have spent a lot of time in the above anti-knife jurisdictions and never had a problem. Dress well, practice good concealment and keep a low profile. You should be fine.