The temple had c. 200 members in 2007.
The Temple of Set was consecrated in Santa Barbara, California during the summer solstice of June 1975, by Michael A. Aquino, in a "greater black magic" ritual that resulted in what Aquino regards as an inspired text titled The Book of Coming Forth by Night. Aquino later stated that the name of the text is an "evident negation" of the name of the Ancient Egyptian Book of Coming Forth by Day, also known as the Book of the Dead. Aquino's working has been compared to Aleister Crowley's "Cairo Working" of 1904, which resulted in the Book of the Law, the central sacred text of Thelema.
The Temple was founded by members of the Church of Satan, who left that organization in 1975 because of administrative and philosophical disagreements with its founder Anton Szandor LaVey. Michael Aquino had joined the Church of Satan in 1969 and had risen rapidly in the Church's hierarchy. Aquino has stated that he believed LaVey to not be merely a charismatic leader but to have been actually appointed by Satan himself (referring to this charismatic authority as the "Infernal Mandate") to found the Church. After the split of 1975, Aquino believed LaVey had lost the mandate, which the "Prince of Darkness" then transferred to Aquino and a new organization, the Temple of Set.
Lewis and Petersen describe the organization's philosophy of being the "intellectual wing of esoteric Satanism", and that it is heavily based on the writings of Aleister Crowley and Western esotericism in general.  The magical rituals of the organization are said to resemble those of the Church of Satan. On the other hand, Granholm states that the Temple cannot be described as Satanic, as the figure of Satan has no prominent position in the Temple's teachings and titles such as Lucifer, Satan or the Devil are seldom used in its infernal materials. However, Temple materials refer to the Church of Satan and have included discussion of the Temple's philosophy as "evolved Satanism", and thus Granholm concludes that the Temple can be characterized as an "actor in the Satanic milieu". Drury and Hume observe that the Temple's philosophy reflects Aquino's academic background and preference for rational thought in contrast to LaVey's sensationalism.
The realization of the true nature of the Setian is termed "becoming" or "coming into being" and is represented by the Egyptian hieroglyphic term kheper, or "Xeper" (a phonetic of _Xpr_), as the Temple of Set prefers to write it. Members attempt "to preserve and strengthen" their "isolate, psyche-centric existence" through adherence to the left hand path. This idea is in supposed opposition to the traditional goal of Hermetic and mystical practices: the surrendering of the ego into a union with God or the universe.
The Temple teaches that the true self, or essence, is immortal, and Xeper is the ability to align consciousness with this essence. Self-initiation is knowledge understood as a conjunction of intellect and intuition. The Temple operates in the context of objective and subjective universes. The objective universe is the natural world and collective meaning systems, while the subjective universe is understood as the individually experienced world and meaning system. Black magic is used by the magician to "become" by causing alterations in the psyche and the world. Lesser black magic is used to manipulate the objective, greater black magic the subjective universes. Initiated members consider themselves beings on a path to self-deification.
The figure of Set, also called the Prince of Darkness, is understood as a principle, but is not worshipped as a god. He is a "role model" for initiates; a being totally apart from the objective universe. Set is considered ageless and the only god with independent existence. Set is described as having given humanity, through the means of non-natural evolution, the "Black Flame" or the "Gift of Set"; a questioning intellect which sets humans apart from nature and gives us "isolate self-consciousness" and the possibility to attain divinity.
The structural design of the Temple of Set places the individual initiate at its center while adhering to a degree structure influenced by the Church of Satan and Aleister Crowley's A.'.A.'. An "atmosphere of congregation" is strongly discouraged with emphasis instead being on the individual's Xeper or self-realization and development.
The Temple of Set recognizes several stages or degrees of initiation. The degrees indicate the individual Setian's development and skill in magic. The degree structure is based on that of the Church of Satan, which in turn was based on the degrees of the Hermetic Order of the Golden Dawn. The Temple terms the progression through degrees as "recognitions", because the organization's philosophy sees that the individual member initiates himself and the Temple merely acknowledges this by granting the degree.
These degrees are:
The priesthood of the Temple of Set consists of members holding the third degree or higher. Full membership comes with recognition to the second degree. Many members do not advance beyond the second degree, nor is this expected of them, as while the first and second degree members use the organization's teachings and tools for their own development, the priesthood involves greater responsibilities towards the organization, such as being its official representatives. Recognition is performed by members of the priesthood. The fourth degree, which is acknowledged by the high priest/priestess, entails that the individual is so advanced in his magical skills that he is able to found his own school of magic, represented in the different orders of the Temple. The fifth degree can only be awarded by the unanimous decision of the Council of Nine and by the approval of the high priest/priestess. A fifth degree member has the power to utter and define a concept which somehow affects the philosophy of the organization, such as the concept of Xeper defined by Michael Aquino in 1975. Only a handful of members have attained this degree and most "fifth-degree" concepts defined in such a manner are no longer studied in the organization. The final sixth degree represents a Magus "whose Task is complete". This degree is held by a very select few in the Temple, although any fifth-degree member can assume the sixth degree based on his own assessment.
The Temple adheres to selective membership policies; fewer than half of all applicants are accepted for full membership within the two year recognition period. The Temple's membership does have a fairly large turnover rate; most members leave eventually for a wide variety of reasons. Only a minority of members remain with the Temple more than a decade. Members pay a membership fee. The Temple admits members on all continents except Antarctica, though it is largely a U.S.-based organization.
All officers and workers within the Temple of Set are volunteers. Some receive reimbursement for expenses incurred for the Temple; none receive a salary and all officers are selected from within the Priesthood.
The organization is led by a high priest/priestess, who is also the public face of the Temple. The high priest is chosen among fourth or higher degree members by the chairman of the Council of Nine. This ruling council has nine members chosen from the priesthood (third degree or higher), whose mandate lasts for nine years with a new member being elected every year. The chairman of the council is chosen from among the council members each year. The council has the ultimate ruling power in the Temple and even the high priest is responsible to it. The Temple also has an executive director, whose task is to deal with administrative issues.
Since its founding in 1975, the temple has had the following high priests/priestesses:
In addition to the international organization, the Temple sponsors initiatory Orders and Elements and local groups called Pylons. Pylons are intended to facilitate the initiatory work of the Temple's members by conducting meetings where discussions and magical works take place. Members usually join the Pylon located geographically closest to them. Correspondence- or Internet-based Pylons also exist. A Pylon is led a by a second-degree (or higher) member who is called Sentinel.
Elements are loosely structured interest groups, where specific themes and issues are addressed. They can be open for non-members and are commonly in operation only for short periods. Topics of interest include, for example, animal rights.
Orders can be understood as schools of different aspects of magic providing different paths of initiation. Orders are led by grand masters, who will usually be the founder of the order. In longer-lived orders the founder may have a successive grand master. Orders are founded by members of the fourth degree. When a member reaches the second degree of initiation, they are expected to join an order of his choosing.
The Temple of Set holds an annual conclave where members of the Temple meet and exchange ideas. Workshops are held in which members discuss a wide variety of topics and activities. The conclave usually lasts about a week and is held in various global locations. There are also occasional regional gatherings, organized and attended by interested Setians, at their own initiative.