The tradition of the ordained monastic community (sangha) began with the Buddha, who established orders of monks and later of nuns. The procedure of ordination in Buddhism is laid down in the Vinaya and Patimokkha or Pratimoksha scriptures. There exist three intact ordination lineages nowadays in which one can receive an ordination according to the Buddha's teachings:
Saicho repeatedly requested that the Japanese government allow the construction of a Mahayana ordination platform. Permission was granted in 822 CE, seven days after Saicho died. The platform was finished in 827 CE at Enryaku-ji temple on Mount Hiei, and was the first in Japan. Prior to this, those wishing to become monks/nuns were ordained using the Hinayana precepts, whereas after the Mahayana ordination platform, people were ordained with the Bodhisattva precepts as listed in the Brahma Net Sutra.
Pabbajja is an ordination procedure for novice Buddhist monks in the Theravada tradition.
The legitimacy of fully ordained nuns (bhikkhuni/bhiksuni) has become a significant topic of discussion in recent years. Texts passed down in every Buddhist tradition record that Gautama Buddha created an order of fully ordained nuns, but the tradition has died out in some Buddhist traditions such as Theravada Buddhism, while remaining strong in others such as Chinese Buddhism (Dharmaguptaka lineage). In the Tibetan lineage, which follows the Mulasarvastivadin lineage, the lineage of fully ordained nuns was not brought to Tibet by the Indian Vinaya masters, hence there is no rite for the ordination of full nuns. However th 14th Dalai Lama has endeavored for many years to improve this situation. In 2005, he asked fully ordained nuns in the Dharmaguptaka lineage, especially Jampa Tsedroen, to form a committee to work for the acceptance of the bhiksuni lineage within the Tibetan tradition, and donated €50,000 for further research. The "1st International Congress on Buddhist Women’s Role in the Sangha: Bhikshuni Vinaya and Ordination Lineages" was held at the University of Hamburg from July 18–20, 2007, in cooperation with the University’s Asia-Africa Institute. Although the general tenor was that full ordination was overdue, the Dalai Lama presented a pre-drafted statement saying that more time was required to reach a decision, thus nullifying the intentions of the congress.
In Medieval Sōtō Zen, a tradition of posthumous ordination was developed to give the laity access to Zen funeral rites. Chinese Ch’an monastic codes, from which Japanese Sōtō practices were derived, contain only monastic funeral rites; there were no provisions made for funerals for lay believers. To solve this problem, the Sōtō school developed the practice of ordaining laypeople after death, thus allowing monastic funeral rites to be used for them as well.