Clapham South is a station on London Underground's Northern line between Clapham Common and Balham. The station is located at the corner of Balham Hill (A24) and Nightingale Lane, at the southern edge of Clapham Common. It is in both Travelcard Zone 2 and Travelcard Zone 3.

The Northern line is a London Underground line that runs from North London to South London. It is printed in black on the Tube map. The Northern line is unique on the Underground network in having two different routes through central London, two southern branches and two northern branches. Despite its name, it does not serve the northernmost stations on the Underground, though it does serve the southernmost station at Morden, the terminus of one of the two southern branches.