It is generally agreed that there were three stages of initiation. First, was the introduction into the Lesser Mysteries. Next, was the celebration of the Greater Mysteries, or telete, and finally, the highest step of initiation, the epopteia. The initiates were called the mystai and each had a sponsor, called the mystagogos.

The Lesser Mysteries were held annually in the early spring. Little of their exact nature is known, other than that they were meant to prepare and purify the initiate for the Greater Mysteries. It has been proposed that these mysteries were celebrated at Agra and were presided over by Persephone. Dancing, reenactments of the myth of Demeter, a sacred meal, and the bearing of the sacred vessels, known as the Kernophoria, were most likely all performed. The initiates would have fasted, made sacrifices, worshipped, and participated in ritual bathing in order to make themselves ready for the Greater Mysteries.

The Greater Mysteries were celebrated annually in the fall. At this time, the entire Greek world declared a truce for 55 days in honor of the mysteries. The Greater Mysteries themselves lasted for nine days. The Mysteries began with a celebration march from Athens to Eleusis, with the Hiera (sacred objects) carried ceremoniously along, obscured in special containers. This procession occurred after several days of preparation and sacrifices.