Gardnerianism as a distinct Tradition began with the writings of Gerald B. Gardner. He was initiated into the New Forest coven in England by "old Dorothy" Clutterbuck. During World War II, Gardner participated in the efforts of British Witches, led by Dorothy Clutterbuck, to turn back Germany's invasion troops. Gardner was active in the Craft and published a fictional novel about medieval Witchcraft in 1949. He started a Museum of witchcraft on the Isle of Man after the 1951 repeal of the last anti-witchcraft law in England. Coming out publicly as a Witch in 1954, he published "Witchcraft Today". At that time, he believed the Craft was dying out - most of the members were older and few young members were being initiated. Gardner strongly believed not only in reincarnation, but that he would be reborn to the craft. If it died out, this could not be, and so he dedicated himself to reviving the Craft. Unable to directly reveal much of his coven's workings, he developed a system that was a synthesis of various elements from Masonic ritual, ceremonial magick, French Mediterranean Craft and the teachings of his coven. Gardner and later Doreen Valiente, rewrote some of the ritual, improving its poetic qualities and adding yet another dimension. They became the basis of Gardnerianism, and those who practiced these rituals as handed down (not as published) became known as Gardneians. The existence of the earlier New Forest coven is unproven, and may not be particularly important. What can be proven is that Gerald Gardner, Doreen Valiente, and their associates did develop a ritual and symbolic system, drawing from many sources including their own inspirations. Their single greatest innovation was to make the Goddess their main focus. The fruit of that generation's research, innovation and creativity was a strong and flexible ritual structure that forms a foundation for the research, innovation and creativity of later generations.

Gardnerianism, like much of the craft, is an initiatory, Mystery Tradition. To become a member of the Tradition, an individual must be initiated by a Gardnerian who was initiated by a Gardnerian, on back to Gardner and his High Priestesses, and the initiation ritual used must be the Gardnerian ritual. Initiation is more than a rite of passage that unites the participants. They have not only undergone a similar death and rebirth but are reborn into a particular world. That world is a microcosm of the universe with a unique psychic pattern of the created by the particular ritual, energy current, and vibration of the Deity names used by the participants. They take on the group karma of their new family and clan, and they add to it as well. They also take an oath of secrecy. From a more eclectic Gardnerian viewpoint, any initiation ritual that is based on the Gardnerian structure and contains certain elements is a valid Gardnerian initiations. Lineage - the sense of family and continuity - is intensely important to Gardnerians. Any variants on initiation or elevation rituals must be checked with the Priestess immediately senior to the one making the changes. It is pointed out that Neo-Gardnerian or Gardnerian based groups using the published versions of Gardnerian rituals, while performing and having perfectly valid initiatory experiences, are not being "reborn" into the same psychic pattern as that of the Gardnerian Tradition. A real difference exists in the energy they draw on and the psychic patterning that is being done. No amount of book knowledge can ever replace human contact and the feeling of belonging to a loving family. Gardnerianism as a Tradition has a body of rituals passed down from Gardner that helps to form the core identity-a shared current of energy which is added to and drawn on by all the initiates, secret Deity names, and a specific group Karma. It also has a hierarchical form of leadership, a three degree systems of training, experienced and knowledgeable Witch Queens and Magus's (high Priestesses and High Priest who have successfully trained a coven to the point where another coven has hived off from theirs) from which to draw on. And there is an oath of secrecy.