Cachan (French pronunciation: [kaʃɑ̃] ⓘ) is a commune in the southern suburbs of Paris, France.

The prestigious École Spéciale des Travaux Publics is located there.

Some others see a connection with the verb "to hunt" (captiare in Vulgar Latin, chacier in Old French).

Cachan was originally a hamlet within the commune of Arcueil, later renamed Arcueil-Cachan.

Cachan is served by two stations on Paris RER line B: Arcueil–Cachan and Bagneux.