Mass. Gen. Laws ch. 7 § 5
The secretary may, with the consent of the governor, appoint a first deputy commissioner of administration who shall also serve as undersecretary. The first deputy commissioner shall be a person of ability and experience; shall serve at the pleasure of the secretary; shall receive such salary as the secretary, with the approval of the governor, shall determine, and, shall devote the first deputy commissioner's entire time to the duties of the first deputy commissioner's office. The first deputy commissioner shall exercise such authority and discharge such duties of the secretary as the secretary may delegate to the first deputy commissioner; and in the absence or incapacity of the secretary or in the event of a vacancy in the position of the secretary, the said first deputy commissioner shall act as the secretary until the absence or incapacity shall have terminated or the vacancy shall have been filled.
Mass. Gen. Laws ch. 7, § 5