Can one adopt somebody that is 18 years old but is still a high school student?

Answer

A person who has reached the age of eighteen in most states is considered an adult, however in Alabama and Nebraska the age would be 19 and in Mississippi and Pennsylvania the age would be 21, so in theory it is possible but not practical. The court would more than likely amend an adoption petition to one of legal guardianship unless there were mitigating circumstances. One such factor would be if the person were in some way disabled as defined by the state laws and/or SSA guidelines.

Answer

In some states it's possible to do an adult adoption long after they turn 18.