Mass. Gen. Laws ch. 4, § 4: Mode of acceptance of statute by municipality or district

Section 4. Wherever a statute is to take effect upon its acceptance by a municipality or district, or is to be effective in municipalities or districts accepting its provisions, this acceptance shall be, except as otherwise provided in that statute, in a municipality, by vote of the legislative body, subject to the charter of the municipality, or, in a district, by vote of the district at a district meeting.