Dianic Wicca is Goddess worship without a god, practised in most of its lines by women only, and it came out of the second-wave feminist movement as much as out of the Craft.
Zsuzsanna Budapest, a Hungarian emigre, founded the Susan B. Anthony Coven Number One at the winter solstice of 1971 in Los Angeles, and described it as the first women-only coven. Its theology is effectively monotheistic: a single Great Goddess of whom all named goddesses are aspects. The Horned God, who stands opposite the Goddess in Gardnerian practice and supplies that tradition's polarity, is simply absent.
The tradition's working assumption is that women need a religious space of their own; that the divine imaged as female does something for women that the divine imaged as male does not; and that the passages of a female life (menarche, childbirth, menopause), are proper subjects of religion and have been treated as improper ones. Healing, self-defence and the recovery of a female religious history are recurring themes.
Its historical claims need the same handling as the rest of Wicca's. Budapest drew on Charles Leland's Aradia of 1899 and on the idea of a suppressed women's tradition surviving the witch trials. The witch-cult thesis is rejected by historians, and the trials were a persecution built on a fantasy rather than the destruction of an existing religion. What Dianic Wicca actually is, is new. Being new is not a criticism.
The name is taken from Diana, the huntress of Roman religion, and from the medieval and early modern accounts of a Diana cult that Leland drew on. Neither supplies a lineage, and the tradition has not needed one to work.