Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 44, § 55B

All moneys held in the name of a city, town, district or regional school district or any other account under the jurisdiction of a city, town, district, or regional school district or officer thereof, which are not required to be kept liquid for purposes of distribution, shall be invested in such a manner as to require the payment of interest on the money at the highest possible rate reasonably available, taking account of safety liquidity and yield. All officers of a city, town district or regional school district who control the investment of such funds shall invest them prudently, consistent with the provisions of sections fifty-four and fifty-five and, if the funds are the result of gift or grant or bequest, the terms of such gift or grant or bequest, so as to accrue the highest amount of interest reasonably available on such funds taking account of safety, liquidity and yield. The provisions of section sixty-two shall not apply to this section.