Mass. Gen. Laws ch. 142 § 3A
Every apprentice shall before starting his apprenticeship file an application, accompanied by the appropriate fee, with the examiners, requesting that he be issued an apprentice license. Said application shall be made on a form to be furnished by the examiners, and shall require the applicant to state his age, the date on which he is to commence his apprenticeship, the name and address of his employer, and such other information as the examiners may require. Upon receipt thereof the examiners shall license said applicant as an apprentice and shall forthwith mail to him a certificate to that effect.
A person may be employed as an apprentice plumber by a master plumber only. A person may be employed as an apprentice gas fitter by a master gas fitter only. Such apprentices shall work under the direct supervision of a master plumber or a journeyman plumber or a master or a journeyman gas fitter. A master plumber or a master gas fitter may employ one or more apprentices but not more than one apprentice may work under the direct supervision of a master plumber, a master gas fitter or a journeyman plumber or a journeyman gas fitter.
Notwithstanding the provisions of this section, students in a vocational school accredited by the department of education, under the direct personal supervision of a master plumber or a journeyman who is certified as an instructor by the division of occupational education in said department shall be permitted to engage in an on-the-job training program, so-called, on installations approved by the examiners and conducted in cooperation with such a vocational school.
The examiners may formulate rules and regulations relative to said on-the-job training program.
Mass. Gen. Laws ch. 142, § 3A