Sullivan Square station is a rapid transit station on the MBTA subway Orange Line, located adjacent to Sullivan Square in the Charlestown neighborhood of Boston, Massachusetts. It is a major transfer point for MBTA bus service, with 10 routes using a two-level busway. The station has two island platforms serving the two active Orange Line tracks plus an unused third track. The Haverhill Line and Newburyport/Rockport Line pass through the station on separate tracks but do not stop.