As tradition goes, a visitor to the oracle first sacrificed an animal. The omens were noted as to whether it was a good day to ask the oracle and then the visitor waited in the room outside the Adyton. Only the priestess could enter the Adyton. The day's order of questions was determined by random lot. Questions, written on leaden tablets, were then passed in to the Pythia, or priestess. This position was originally filled by a young woman but over time, older women became Pythia. At the height of Delphic fame, there were three Pythiae at one time.

The Pythia would cleanse herself in the Kastalian Spring and then seat herself on a tripod which was located over a chasm in the Adyton. An omphalos and a spring called the Kassiotis were also supposed to be located in this room. Some say that she chewed laurel leaves (the tree sacred to Apollo) and inhaled exhalations, or gas, which issued from the chasm. The overall effect was that the Pythia entered a trance-like state in which she spoke incoherently. A priest or poet nearby would then interpret these noises into verse. Often, the Pythia's answers were esoteric and carried double meanings, misleading visitors more than if they had ever asked.

However, this traditional version is by no means accepted by all scholars. Some, like Joseph Fontenrose, point out that no concrete evidence of a true chasm or gases has ever been found. Classical sources mentioning the trance and exhalations are vague and can be interpreted in many ways. Fontenrose also argues that the historical, trustworthy accounts of the Pythia usually depict her as calm, sane, speaking face to face with her visitor, and giving oracles which are simple and clear. The more fantastic a story becomes, such as mythological heroes or word of mouth accounts, the more devious and vague the Pythia becomes. Little of the actual proceedings in the oracle were recorded and there are many mysteries left to be solved.