On the first day, a general proclamation would be issued and preparations began. On the second day, shouting "to the sea, oh mystai!", the initiates would head to the sea in the early morning hours and wash themselves as well as a pig that each carried. After the cleansing, the initiates would return to Athens with their pigs and sacrifice them. What occured on the third day is not exactly known, though it is supposed that a general sacrifice on behalf of the city was made.

The fourth day was reserved for a repetition of the rites of the first three days for anyone who had arrived late to Athens and missed the purifications and sacrifices. This practice was in honor of Asklepios, the god of healing, who himself arrived late for the Greater Mysteries. For the rest of the initiates, it was most likely a day of rest.

The fifth day was the actual day of the great procession from Athens to Eleusis. The priests dressed in their finest robes, the pilgrim initiates were decked with myrtle, carrying staves specifically made for this journey, and the wooden statue of Iachhos was carried in front by his priests. The procession crossed fourteen miles of land (some who could afford took carriages) and the statue of Iachhos, bearing a torch, led the way. Along the way, a strage event occurred, in which the inhabitants of the area behind the bridge of the Rheitoi tied woolen, saffron ribbons around right hand and left legs of the initiates. The meaning of this ritual is unclear. A second tradition occurred at the bridge crossing over the Eleusinian Kephisos. Men in hoods stood upon the bridge and jeered and hurled insults at any initiate who was an important person ... perhaps to encourage humbleness. Finally, the procession, traveling down the Sacred Way, would reach the Great Forecourt of the sanctuary and celebrations and dancing would begin soon thereafter. In the two thousand years that the Greater Mysteries were celebrated, this procession was only canceled once, when Alexander the Great destroyed Thebes.