Strange History

The Dancing Plague of 1518: They Danced Until They Dropped

By The Unsolved Report Editorial Team · Last reviewed 2026-06-19

In July 1518, hundreds of people in Strasbourg danced uncontrollably for weeks. Here are the documented facts, the genuine open mystery, and the leading theories.

In the punishing summer heat of July 1518, a woman stepped into a narrow cobbled street in Strasbourg and began to dance. There was no music, no festival, and no apparent reason. She danced through the day and into the night, and when she finally collapsed from exhaustion, she rose and danced again. Within a week, dozens of her neighbors had joined her. Within a month, as many as 400 people were caught in the same relentless compulsion.

This is not a folk legend dressed up as history. The dancing plague of 1518 is one of the best-documented strange events of the early modern era, recorded by physicians, city officials, and chroniclers of the time. And yet, five centuries later, no one can say with certainty what caused it.

The Documented Facts

The outbreak is unusually well attested for a medieval-era event. As the Encyclopaedia Britannica notes, the episode is preserved across multiple contemporary records, including physician notes, cathedral sermons, regional chronicles, and notes issued by the Strasbourg city council itself (Britannica; Wikipedia summary of sources). That paper trail is what separates 1518 from vaguer tales of "dancing mania" elsewhere in medieval Europe.

The traditional account names the first dancer as Frau Troffea, who began dancing in the street outside her home in July 1518 (History). According to the Public Domain Review's survey of the chronicles, the date often cited is July 14, 1518, though that precise day comes from later compilations rather than a single contemporary diary entry (Public Domain Review).

What happened next is consistent across the major sources. Within roughly a week, more than 30 other people had been drawn into the same uncontrollable dancing. By August, the count had swelled to as many as 400 afflicted citizens (Britannica; History). The dancers did not appear to be celebrating. Eyewitness-derived accounts describe people moving in apparent distress, crying out, begging for help, and continuing anyway.

The response that made it worse

The city's reaction is one of the most striking documented details. Rather than confining the dancers, Strasbourg's authorities initially decided the cure was more dancing. As Britannica records, officials set aside guildhalls for the afflicted, hired musicians to accompany them, and even brought in strong, healthy dancers to keep the sufferers moving (Britannica). The strategy backfired badly and seems to have spread the contagion further (National Geographic).

When that failed, the council reversed course, banning public dancing and music. By September, the surviving dancers were reportedly led on a pilgrimage to a shrine of Saint Vitus, the saint associated with dancing afflictions, located in the hills near Saverne (Public Domain Review; Wikipedia). Soon after, the episode faded as mysteriously as it had begun.

The Genuine Open Question

Two questions remain genuinely unresolved, and it is important to keep them separate.

The first is how many people died — or whether anyone died at all. A widely repeated figure claims that at the peak, around 15 people perished each day from strokes, heart attacks, or sheer exhaustion. But this is where the evidence gets thin. As multiple sources point out, the contemporary Strasbourg records do not actually state a death toll, and some note that no surviving source from the time of the events confirms any fatalities (Wikipedia). The dramatic "fifteen a day" claim traces to later accounts rather than the 1518 documents themselves (Public Domain Review). So the popular image of hundreds dancing to their deaths should be read with caution: prolonged, exhausting dancing is well documented, but the body count is not.

The second and deeper question is simply why it happened. The dancing is real and recorded. Its cause is not. No single explanation has been confirmed, which is exactly why the event still fascinates historians and physicians alike.

Theories and Interpretations

What follows is informed speculation. None of these explanations is settled fact; each is a scholarly attempt to fit the documented behavior to a known mechanism.

Theory 1: Mass psychogenic illness (the leading view)

Speculative, but the most widely accepted. American medical historian John Waller, whose work is the standard modern reference, argues the outbreak was a form of mass psychogenic illness — what older texts called "mass hysteria" (Britannica). In his account, Strasbourg in 1518 was a city under extraordinary strain: recent famines, plus diseases such as smallpox and syphilis, had pushed the population to a psychological breaking point (Britannica). Into that environment came a potent shared belief — the conviction that an angry Saint Vitus could curse sinners with uncontrollable dancing. Waller suggests that, given enough collective stress and a firm shared expectation, that fear could become self-fulfilling, spreading person to person through suggestion (National Geographic). Modern scholars have extended this reading, framing the dancing as a collective trauma response in a community battered by floods, famine, and disease (National Geographic).

Theory 2: Ergot poisoning

Speculative, and largely set aside by current scholars. In the 20th century, investigators proposed that the dancers had eaten rye bread contaminated with ergot, a fungus that produces compounds related to LSD and can cause convulsions and hallucinations (Britannica). It is a tidy biological story, but it has serious problems. Waller and others note that ergotism typically restricts blood flow to the limbs — making sustained, days-long dancing physically implausible — and that contemporary accounts lack the gangrene and blackened extremities ergot poisoning usually produces (National Geographic; Wikipedia).

Theory 3: Heretical sects and religious ritual

Speculative, and a minority view. Sociologist Robert Bartholomew has suggested the dancers may have been members of a fringe religious group performing ecstatic dance to attract divine favor (Britannica). Most historians find this less persuasive than the stress-and-suggestion model, given how the chronicles describe sufferers as distressed rather than devout.

Theory 4: The period's own explanations

The people of 1518 had their own theories, recorded in the sources: divine punishment, demonic possession, and the medical idea of "overheated blood" (Britannica; Wikipedia). These tell us less about the cause than about how a frightened community made sense of something it could not control.

Why It Still Matters

The dancing plague of 1518 endures because it sits at a rare crossroads: the what is documented, and the why is honestly unknown. Hundreds of real people, in a real city, did something inexplicable and exhausting for weeks — and the best minds studying it still hedge their conclusions. That gap between solid record and open question is the whole story.

Sources and Further Reading

Encyclopaedia Britannica — "Dancing plague of 1518"
HISTORY — "What Was the Dancing Plague of 1518?"
National Geographic — "What caused Strasbourg's dancing plague of 1518?"
The Public Domain Review — "The Dancing Plague of 1518"
Wikipedia — "Dancing plague of 1518" (useful for its catalog of contemporary chronicle sources)
John Waller, A Time to Dance, a Time to Die: The Extraordinary Story of the Dancing Plague of 1518 (Icon Books, 2009) — the standard modern scholarly treatment.

Sources & further reading

https://www.britannica.com/event/dancing-plague-of-1518
https://www.history.com/articles/what-was-the-dancing-plague-of-1518
https://www.nationalgeographic.com/history/article/dancing-plague-of-1518-strasbourg-choreomania
https://publicdomainreview.org/essay/the-dancing-plague-of-1518
https://en.wikipedia.org/wiki/Dancing_plague_of_1518
https://www.britannica.com/biography/John-Waller