Mass. Gen. Laws ch. 31 § 54
If five per cent or five thousand of the registered voters in a city file with the city clerk a petition requesting that the question of accepting the applicability of the civil service law and rules to either or both of the offices specified in clause (2) of section fifty-one or to any city office as provided in clause (b) of section fifty-three be placed on the official ballot, the clerk shall, if he finds such petition to be in order, place such question on the official ballot for the next regular city election occurring more than sixty days after the filing of such petition.
If five per cent or one thousand of the registered voters in a town authorized under section fifty-two to accept the applicability of the civil service law and rules to the official service or to the labor service, or to both services, or to any one or more of the positions or forces specified in clauses (a) through (h) of said section file with the town clerk a petition requesting that the question of accepting such applicability to either or both of such services, or to any one or more of such positions or forces, be placed on the official ballot, the clerk shall, if he finds such petition to be in order, place such question on the official ballot for the next regular town election occurring more than thirty days after the filing of such petition.
If five per cent of the registered voters in any town file with the town clerk a petition requesting that the question of accepting the applicability of the civil service law and rules to a town office as provided in clause (b) of section fifty-three be placed on the official ballot, the clerk shall, if he finds such petition to be in order, place such question on the official ballot for the next regular town election occurring more than thirty days after the filing of such petition.
Mass. Gen. Laws ch. 31, § 54