Dancing mania (also known as dancing plague; choreomania; St John's Dance and; historically; St. Vitus' Dance) was a social phenomenon that occurred primarily in mainland Europe between the 14th and 17th centuries. It involved groups of people dancing erratically; sometimes thousands at a time.

The mania affected men; women; and children; who danced until they collapsed from exhaustion. One of the first major outbreaks was in Aachen; Germany; in 1374; and it quickly spread throughout Europe; one particularly notable outbreak occurred in Strasbourg in 1518; France.

Affecting thousands of people across several centuries; dancing mania was not an isolated event; and was well documented in contemporary reports. It was nevertheless poorly understood; and remedies were based on guesswork. Generally; musicians accompanied dancers; to help ward off the mania; but this tactic sometimes backfired by encouraging more to join in. There is no consensus among modern-day scholars as to the cause of dancing mania.