South Street station is a light rail surface stop on the MBTA Green Line B branch, located in the median of Commonwealth Avenue east of South Street in the Brighton neighborhood of Boston, Massachusetts. South Street is the lowest-ridership stop on the B branch, with just 214 daily boardings by a 2011 survey. Track work in 2018–19, which included replacement of platform edges at several stops, triggered requirements for accessibility modifications at those stops. Design for South Street and four other B Branch stops was 30% complete by December 2022. A design shown in March 2024 called for Chestnut Hill Avenue station and South Street station to be consolidated, with a single station located between Chestnut Hill Driveway and Chestnut Hill Avenue. In May 2024, the Federal Transit Administration awarded the MBTA $67 million to construct accessible platforms at 14 B and C branch stops including the consolidated station. , construction is expected to start in fall 2025.