The holiday of Mardi Gras is celebrated in all of Louisiana, including the city of New Orleans. Celebrations are concentrated for about two weeks before and through Shrove Tuesday, the day before Ash Wednesday (the start of lent in the Western Christian tradition). Usually there is one major parade each day (weather permitting); many days have several large parades.

The largest and most elaborate parades take place the last five days of the Mardi Gras season. In the final week, many events occur throughout New Orleans and surrounding communities, including parades and balls (some of them masquerade balls).

Float riders traditionally toss throws into the crowds. The most common throws are strings of colorful plastic beads, doubloons, decorated plastic "throw cups", Moon Pies, and small inexpensive toys. Major krewes follow the same parade schedule and route each year.

The parades in New Orleans are organized by social clubs known as krewes; most follow the same parade schedule and route each year. The earliest-established krewes were the Mistick Krewe of Comus, the earliest, Rex, the Knights of Momus and the Krewe of Proteus.