Mass. Gen. Laws ch. 18A, § 4

There shall be in the department the following bureaus: the bureau of clinical services; the bureau of after-care, delinquency prevention and community services; the bureau of educational services; and the bureau of institutional services. Each bureau shall be under the direction of an assistant commissioner who shall be appointed by the commissioner and who shall not be subject to the provisions of chapter thirty-one and to whom the provisions of section nine A of chapter thirty shall not apply.