The National LGBT Bar Association says it's the first time it will take part in the mass swearing-in that occurs on most days the court is in session.
Association executive director D'Arcy Kemnitz said many members already will be in Washington for President Barack Obama's inauguration on Monday. They'll be sworn in Tuesday.
By custom, a Supreme Court lawyer vouches for prospective members, and Chief Justice John Roberts welcomes them before they swear to support the Constitution.
Openly gay lawyers already practice before the Supreme Court, but Tuesday will mark the first time lawyers will be identified at the ceremony as LGBT Bar members.