Massachusetts General Laws Part II. Real and Personal Property and Domestic Relations (Ch. 183-210) Ch. 210, § 1

A person of full age may petition the probate court in the county where he resides for leave to adopt as his child another person younger than himself, unless such other person is his or her wife or husband. A minor may likewise petition, or join in the petition of his or her wife or husband, for the adoption of a natural child of one of the parties. If the petitioner has a husband or wife living, competent to join in the petition, such husband or wife shall join therein, and upon adoption the child shall in law be the child of both; provided, however, that the prayer of the petition may be granted although the spouse of the petitioner is not a party to the petition if the court finds: (i) the failure of the spouse to join in the petition or to consent to the adoption is excused by reason of prolonged unexplained absence, legal separation, prolonged separation, incapacity or circumstances constituting an unreasonable withholding of consent; (ii) the husband and wife are not in the process of an ongoing divorce; and (iii) the granting of the petition is in the best interests of the child. If a person not an inhabitant of this commonwealth desires to adopt a child residing here, the petition may be made to the probate court in the county where the child resides.

The district or juvenile court may, if it appears necessary or convenient, exercise the powers authorized by this chapter, but only in respect to a pending proceeding before such district or juvenile court.