One month earlier, a draw establishes which Contrade will participate to the race, and seven of those excluded from the previous Palio will be added. The ones excluded take part in the historical parade anyway and have the right to participate to the next Palio.

A draw called "tratta" establish which horse is to be given to each Contrada. From that moment, the rider only has four days to train and familiarize with his steed. The start, also called the "mossa", is one of the peculiarities that make the Palio of Siena unique in its genre.
In effect, no-one can know the moment of the departure. Near the alleyway of the Costarella dei Barbieri, the first nine riders chosen line up "ai canapi", namely they have to enter an area limited by two long ropes one at a time. This is a difficult operation for a number of reasons. On one side, it is not always easy to convince the horses to stay inside the ropes and stand still, because they get anxious when they are near to their own kind.
On the other side, more often the jockeys are late or hinder the operations, in particular those who are either penalized by an unfavourable position or have to mark a rival of another Contrada closely. If this happens, the "mossiere", whose duty is to regulate the departure, can decide to start the competition again. The tenth rider, instead, takes a run and enters when he thinks it is best to, and, therefore, he is the one who starts the race.
Three laps on the square follow during which the jockeys and the horses fight. At the end of these three laps, the horse arriving first to the finishing post (in the same starting area and not on the same starting line) represents the Contrada that will receive the Palio or "cencio". Often, a horse "scosso", namely deprived of its rider, can win. This is not a problem, though, because according to the rules of the Palio it is the horse that wins and it does not matter if its jockey has been unsaddled or if he has decided to abandon the race.
Once received the Palio, a banner painted with the colours of the city, the "contradaioli" go to Provenzano (on July) or to the Dome (on August) and sing a "Te Deum" of thanks before starting the celebrations that will last the whole night in a blaze of chants and flags.