Fancy dress is a direct evolution of the old tradition of masquerade balls, the practice of dressing up in elaborate dresses and suits, combined with extravagant decorated masks concealing the partygoers’ faces. They originated in 15th century Italy as part of the Carnival season, a festive period preceding Lent, where rich foods would be consumed and costumes would be worn as part of a lengthy celebration.
Carnivals never spread too far outside of Italian cities, though the art of the masquerade proved more popular. By the 17th century they were widely used as a part of celebrations across Europe, and reached England in the 18th century.
However, they were soon met with wide moral opposition. Masquerades were limited to the cultured upper classes, and the anonymity they afforded individuals in the public eye often led to casual and unrespectable romantic encounters, which became the topic of many short stories and plays published in the era. Seen as a sign of depravity there were many attempts to deter the practice, but none were successful, particularly after Queen Victoria expressed her affection for the practice herself, cementing the popularity throughout the 19th century and onwards.
In the late 19th and early 20th centuries they became more casual, and a wider selection of the public would indulge in masquerades. Costumes became less extravagant and more topic, with individuals impersonating famous characters from poems and plays, such as the works of Shakespeare or defunct Roman gods. By the 20th century celebrations focused almost entirely on impersonation of some kind of recognisable figure, and the unique extravagance and anonymity of the masquerade began fading into obscurity. Rather than hiding your identity, the intention was to make both your identities clear, who you were and who you had successfully imitated.
From this point onwards fancy dress became recognisable in the form we see it today, simply becoming cheaper and more prevalent as time moved on. But it’s interesting to note the similarities between our current parties and the traditions of old. Much like the masquerades were seen as debaucheries, many use fancy dress today to show a little more skin than they’d usually be permitted, and the old factor of escaping your identity for a night is still present to an extent. Over six centuries we’re still dressing up for similar reasons, it’s just the costumes themselves have changed.