In every state, the birth mother and birth father (if he has established paternity) must consent to an adoption. Either one or both parents may have these rights terminated for an  assortment of reasons, including abandonment, failure to support the child, mental incompetence, or a finding of parental unfitness due to abuse or neglect.

When neither birth parent is available to consent, the responsibility may fall into any of the following groups:
- An agency which has custody of the child
- Any person who has been given custody of the child
- A guardian or guardian ad litem
- The court having jurisdiction over the child
- A close relative of the child
- A "next friend" of the child, who is a responsible adult appointed by the court