The Vajrayana, the `diamond' or `thunderbolt' way, is based on the doctrines and philosophical thinking of the Mahayana. It therefore accepts the Bodhisattva ideal that enlightenment should be sought for the benefit of all beings. The Vajrayana is intended for practitioners who have trained within the Mahayana but who instead of following the slow path of the perfections, the prajñaparamita, desire a faster route to enlightenment which may be achieved within one lifetime. The path is based on texts called tantras which were written in India up until around 1200CE but which were considered like the late Mahayana texts to be the word of the Buddha himself, revealed only to those who were ready to hear. The tantras (there are approaching 500 tantras in the Tibetan canon), contain detailed instructions on how to visualize complex worlds of Buddhas and Bodhisattvas and also details of how to perform magical transformatory rituals incorporating powerful sounds called mantras.
     Vajrayana practice reflects Madhyamaka, Yogacara and Tathagatagarbha thought. Samsaric and Nirvanic worlds are considered to be the same making it possible for practitioners not only to regard themselves as identical to the deities whom they visualize but also to make use of the body's natural energies, such as hatred, greed and sexual desire, to bring about transformations at subtle levels. Many of the tantras are obscure and can only be interpreted by experienced teachers who stand in place of Sakyamuni Buddha and give formal and often secret initiations to their disciples.

The earliest evidence of Vajrayana practice comes from chapters in Mahayana sutras from the second century CE which incorporate strings of unintelligible syllables which were credited with magical power. At this time this type of practice was a minority interest of monks living alongside non-tantric practitioners under the same monastic disciplinary code.
     By the eighth century CE commentarial literature on the tantras had been developed especially at the new Buddhist universities of Vikramasila and Odantapura. At this stage symbolism, terminology and ritual had been established and the practices were less of a minority activity although still restricted to monastics. Between the ninth and tenth centuries practitioners known as Maha-siddhas who were highly accomplished yogins travelled around the country, often with young female consorts. Many of these practitioners challenged religious orthodoxy. They were not subject to monastic rules and they demonstrated the union of male and female both literally and as representative of the union between the female wisdom (prajna) and the male skilful means (upaya).      By the middle of the eleventh century tantras such as the Kalacakra represented a complex synthesis of Buddhist and Hindu deities with political and astrological elements.
     Vajrayana practices were introduced into China in the eighth century but were not popular because of their sexual imagery which offended the Chinese sense of morality. Some transmissions did however reach Japan and Korea where Shingon Buddhism (Shingon is the Chinese term for mantra) took root alongside other Mahayana schools. The practices were most popular in Tibet where they were first taken in the seventh and eighth centuries and they became synonymous with Tibetan Buddhism.

Vajrayana Buddhism is by its nature rich in symbolism including the complex and colourful mandalas which decorate the temple buildings and which practitioners visualize as part of meditational practice. The most characteristic symbol is the vajra from which this type of practice takes its name. The vajra takes the form of a single or double sceptre and is derived from the sceptre of the Hindu god Indra, who used thunder and lightening as his weapons. Later the vajra came to be interpreted as a diamond. The combination of thunderbolt and diamond was used to symbolize the nature of the enlightened mind. As a thunderbolt overcomes all material things, so the enlightened mind can resist all obstacles. As a diamond is clear and bright, so the enlightened mind is empty and indestructible.

It is not possible to estimate the numbers of present day adherents of Vajrayana forms of Buddhism. All Tibetan Buddhism contains elements of Vajrayàna practice and the Shingon school in Japan is said to include ten per cent of the population. Vajrayana practice is now becoming increasingly popular in the Western nations to which Buddhism has spread particularly since the mass exodus of Tibetans from Tibet in 1959.

The school has no headquarters or main centre.