Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 51, § 62

When a caucus is called, the registrars, on the request of the chairman of the ward or town committee of the party whose caucus is to be held or of the person designated to call the caucus to order, shall furnish him for use in the caucus a certified copy of the last published voting list of the town, or of the ward of the city for which the caucus is to be held, adding thereto the names of voters registered since such publication. Said lists, if intended for use in the caucus of a political party, shall contain the party enrollment of voters whose names appear thereon established as provided in sections thirty-seven and thirty-eight of chapter fifty-three.