Mass. Gen. Laws ch. 43B § 7
The city or town clerk within ten days of the election shall notify the nine candidates elected to the charter commission of the initial charter commission meeting. At such initial meeting a charter commission shall promptly organize by the election from any of its members a chairman, a vice chairman and a clerk and shall file a notice of such organization with the city or town clerk. A charter commission shall continue to exist until thirty days after the election at which its charter adoption or revisions proposal, if any, is required to be submitted to the voters under this chapter or until thirty days after submission to the city council or town meeting of a final report recommending no new charter or revision. If any member dies, resigns or ceases to be a registered voter of the city or town, or if a failure to elect or any other vacancy occurs, it shall be filled by the election of any registered voter of the city or town by vote of a majority of the remaining members. The commission may continue to act notwithstanding the existence of any vacancy. Members shall serve without compensation but shall be reimbursed from the commission's account for expenses lawfully incurred by them in the performance of their duties.
Mass. Gen. Laws ch. 43B, § 7