According to the "Seinfeld Orthodoxy," Festivus is December 23. However, in the real world, many people celebrate it at other times of year, some throwing Festivus parties for friends and others they choose to be with in early December before they have to go home and be with the people they don't want to be with, namely their families. There are prominent Festivi all times of year. But if one adheres to the word of the character Frank Costanza, Festivus is the 23rd.