Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 147, § 39

Except as hereinafter provided, no contestant under 18 years of age or who has reached his thirty-fifth birthday shall be permitted to engage in a boxing, kickboxing, mixed martial arts or other unarmed combative sport event, sparring match or exhibition, except that the age requirement shall not apply to a world boxing champion who is still actively engaged as a professional boxer, or to a former boxing champion of the world who has not been inactive as a professional boxer for more than 2 years from the date of his last boxing contest;  provided, however, an amateur boxer shall be allowed to compete as such at the age of 16.  At the discretion of the commission, a professional boxer, kickboxer, mixed martial arts contestant or other unarmed combative sport contestant who has reached his thirty-fifth birthday may be permitted to engage in a match if the contestant has passed a physical examination or is otherwise medically-cleared to participate by a physician selected by the commission.  At the discretion of the commission, an amateur boxer who has reached his sixteenth birthday but has not yet reached his eighteenth birthday may be licensed as a professional boxer.  The foregoing shall not apply to courses of instruction in boxing, kickboxing, mixed martial arts or other unarmed combative sport sponsored and conducted by recognized boys and girls clubs, youth organizations, private clubs and athletic associations, schools or colleges, municipal or state park or recreational departments, law enforcement organizations or incorporated, private, nonprofit boxing teams, under the supervision of qualified instructors and directors.

No person under the age of 16 shall be admitted to, or be present at, a professional match or exhibition unless accompanied by an adult.