Mardi Gras celebrations existed before Europeans came to the New World. Ancient Romans observed what they called the Lupercalia, a circus-type festival that was, in many respects, quite similar to the present day Mardi Gras celebration during mid February. There festival honored the Roman deity. Although Lupercus is derived from the Latin Lupus, the original meaning of the word has become obscured over the passage of time and may have not have any relations to today’s Mardi Gras.

As Christianity became popular in Rome, the church leaders decided it should incorporate certain aspects of the Mardi Gras rituals into the new faith rather than attempt to abolish them altogether. This resulted in a Christian interpretation of the ancient Mardi Gras custom, and the Mardi Gras Carnival became a time of abandon and merriment, which preceded the Lenten period. During these times, there would be Mardi Gras feasting for several days, and participants would indulge in voluntary madness by donning Mardi Gras masks, clothing themselves in the likeness of spectres and generally giving themselves up to Bacchus and Venus. All aspects of pleasure were allowed during the Mardi Gras Carnival celebration. Today's modern Mardi Gras celebrations are more reminiscent of the Roman Saturnalia rather than Lupercalia, or be linked to even earlier Pagan Mardi Gras festivals.

Germany holds a Carnival similar to Mardi Gras known as Fasching, which begins on 12th night and continue until Shrove Tuesday. A Mardi Gras Carnival season was also celebrated in England until the 19th Century, originating as a type of "renewal" festival that incorporated fertility motifs and ball games. These Mardi Gras like celebrations frequently turned into riots between opposing villages, followed by feasts of pancakes and the imbibing of alcohol.

It is believed that Mardi Gras was brought to United States in 1699 by the French explorer, Sieur d'Iberville. The Mardi Gras festival had been celebrated as a major holiday in Paris since the Middle Ages. Iberville sailed into the Gulf of Mexico and from there, launched an expedition up the Mississippi River. By March 3, 1699, Iberville had set up a camp on the West Bank of the River, about 60 miles south of the current city of New Orleans. Since it was the day Mardi Gras was being celebrated in France, Iberville named the site Point du Mardi Gras in honor of the Mardi Gras festival.

Still others believe that Mardi Gras was brought to New Orleans in 1827 when a group of students who had recently returned from school in Paris donned Mardi Gras costumes and danced their way through the streets. The students had first experienced this revelry while taking part in Mardi Gras celebrations in Paris. In this version, it is said that the inhabitants of New Orleans were swiftly captured by the enthusiasm and quickly followed suit in the Mardi Gras celebrations.

Mardi Gras celebration fluctuates between Christmas and Lent. Easter is always on a Sunday, but it can be any Sunday from March 23rd through April 25th. Its actual date is the Sunday following the first Full Moon after the Spring Equinox. The Mardi Gras celebration period is always the 47 days that precede this allotted Sunday. However, the beginning of the Mardi Gras Season itself is also fixed, beginning January 6th, which is the Feast of the Ephiphany, otherwise known as Little Christmas or Twelfth Night. Since the date of Mardi Gras varies, the length of Mardi Gras also varies accordingly from year-to-year.

The French definition of "Mardi Gras" is "Fat Tuesday," so named because it falls on the day before Ash Wednesday, the day prior to Lent, a 40 day season of prayer and fasting observed by the Roman Catholic Church which ends on Easter Sunday. The origin of "Fat Tuesday" is believed to have come from the ancient Pagan custom of parading a fat ox through the town streets. Such Pagan holidays were filled with excessive eating, drinking and general rowdiness prior to a period of fasting.