The Wasp is an amphibious assault ship launched in 1987, built by Ingalls Shipbuilding. It's 844 feet long and can carry more than 2,000 Marines and handle a variety of rotor aircraft.
The ship is scheduled for dry-dock maintenance this year.
What the contract modification will cover was not disclosed, but there is speculation it could involve preparing the ship to accommodate F-35 vertical takeoff and landing aircraft.
The undefinitized contract action is worth more than $110 million.
"The contract modification secures a fiscal 2013 dry-docking planned maintenance availability, which includes the planning and execution of depot-level maintenance, alterations, and modifications that will update and improve the ship's military and technical capabilities," BAE said.