Buddhist schools (sometimes referred to as ‘sects’). These are felt by Buddhists to be primarily a matter of lineage more than credal confession. A Buddhist is a Bauddha (Skt., ‘Follower of Buddha’) and takes refuge in the Three Jewels, thus becoming a part of the saṅgha with a particular interpretation of the dharma, and will often refer to a particular person as ‘my teacher’. This teacher will have been certified by another teacher in a lineage which, if complete, can be traced back to the Buddha. Controversies then arise over the authenticity of a lineage and/or the correctness or completeness of its understanding of the dharma. Since divisions over the interpretation of dharma have often impressed scholars as philosophical, they have been called schools rather than sects, or the neutral term ‘tradition’ may be used. Within Tibetan Buddhism the theoretical divisions called siddhānta (Skt., ‘finality’, ‘explanation’) have been translated as ‘system’ although they come closest to being philosophical schools. No one term in Buddhism corresponds to any of these divisions, and for convenience the word ‘lineage’ will be used here.

There are two major lineage groups: Theravāda and Mahāyāna. Vajrayāna is sometimes counted as a third grouping and sometimes as a subset of Mahāyāna. Theravāda is most simply viewed as a single major lineage. Mahāyāna is a family of lineages that may be grouped into two main cultural types: Tibeto-Mongol and Sino-Japanese. Tibeto-Mongol Buddhism sees itself as the inheritor of later Indian Mahāyānist scholar-monks and places much emphasis on philosophical precision. Sino-Japanese Buddhism (which includes Korean and Vietnamese forms) developed lineages independently of Indian Mahāyāna.

Early Buddhism is said to have divided into eighteen lineages on the basis of scholarly disputes about the nature of all three of the Three Jewels. None of the earliest lineages can be clearly identified in later Buddhism, but Theravāda may be seen as the oldest surviving lineage. It has become the dominant form of Buddhism in SE Asia. Theravāda has been repeatedly split over questions of monastic discipline (see VINAYA) and ordination practice, and the relative importance of doctrine and meditation.

Tibetan Buddhism has four main lineages divided into two major groups: Nyingmapa (Tib., ‘Ancient Ones’), a single lineage attributed to the Indian missionary Padmasambhava (9th cent. CE), which arranges the dharma into nine vehicles (Skt., Yāna); and Sarmapa (Tib., ‘New Ones’), a group containing the three lineages of the Later Transmission: Kagyupa founded by Marpa (1012–c.1098), Sakyapa founded by Konchog Gyalpo (1034–1102), and the Gelugpa reform of Tsongkhapa (1357–1419). The Nyingma and Sarma groups differ over their understanding of śunyatā and the interpretation of Tantra. The sub-divisions of the Kagyu are the most complicated. There are two main divisions, Shangpa and Dragpo. The Dragpo has four divisions, of which the Karma Kagyu is the best known. Another division, Phagtru, itself has eight divisions, of which the Drikung and Drukpa are best known. Drukpa has further sub-divided into three. Tsongkhapa's lineage, Gelugpa, attempts a synthesis of what it considers the best features of all Sarma groups. The Dalai Lamas belong to the Gelugpa. The Tibetan lineages spread into Mongolia and mixed with the indigenous shamanism but without producing distinctly new lineages.

Chinese Buddhist lineages may be divided into three main types: modifications of Indian lineages, native scholastic lineages, and native popular lineages. All these lineages interact with each other in complex ways and this classification, although designed to be helpful, is in no way absolute. The major lineages based on Indian forms are one Hīnayāna, Chü-shê or Ābhidharmika; and two Mahāyāna, San-lun or Mādhyamaka, and Fa-hsiang or Yogācāra/Vijñānavāda. These, and many smaller lineages, provided the theoretical basis for the development of the two great comprehensive Chinese systems of T'ien-t'ai, based on the Lotus Sūtra and founded by Hui-ssŭ (515–76); and Hua-yen, based on the Avatamsaka Sūtra and founded by Tu-shun (557–640). Lineages with a wider appeal among layfolk are Zen (Chin., Ch'an), attributed to the Indian missionary Bodhidharma (c.5th cent.) and Pure Land (Chin., Ching-t'u), perhaps founded by Hui-yüan (334–416). During the Sung and Ming Dynasties Zen and Pure Land were synthesized to form the basis of modern Chinese Buddhism.

Korean Buddhist lineages were at first extensions of the Chinese, with the Hua-yen (Hwaŏm) being the most important and forming the doctrinal basis for all later Korean Buddhism. A distinctively Korean lineage, Popsong (Dharma Nature) was founded by Wŏnhyo (617–86) who attempted a comprehensive system based on the Awakening of Faith (Mahāyānaśraddhotpāda-śastra) and the teaching of One Mind. Zen Sŏn was introduced by Pŏmnang in c.630 and sparked a major controversy between itself and scholastic Buddhism (collectively known as Kyo) which still affects Korean Buddhism. Sŏn itself divided into nine lineages, called ‘mountains’, which disputed with each other. The highly respected Master Chinul (1158–1210) attempted to resolve the controversies by teaching the identity of the enlightenment achieved through Sŏn practice and Kyo study, i.e. the identity of the ‘tongueless’ and the ‘tongued’ dharma transmissions. The government forcibly united the lineages at various times, and in 1935 all lineages were unified as the Chogye.

Japan received many of the Chinese lineages through Korea in the 6th cent. CE, with some importance again being given to Hua-yen (Kegon). Kūkai (774–835) combined two streams of Chinese Chen-yen (Vajrayāna) to form Shingon, an original synthesis which became considerably more popular than its parents, and with his ability to align Buddhism with native folk religion he became a cultural hero. Zen and Pure Land have remained distinct lineages in Japan, with three forms of Zen modified from Chinese forms (Sōtō, Rinzai, and Ōbaku) and two main forms of Pure Land (Jōdo and Jōdoshin) developed indigenously by Hōnen (1133–1212) and Shinran (1173–1263) respectively. Nichiren (1222–82) founded a vigorously exclusivist lineage of which a later subbranch, Nichiren Shōshū, is socially (as Sōka Gakkai) and politically (as the Kōmei Party) highly visible in present-day Japan. As Korea has tried to reduce the number of lineages, so Japan has allowed them to proliferate. Nearly 170 lineages, divided amongst 14 major groupings, are currently listed by the Japanese Agency for Cultural Affairs.

Vietnam received lineages from the rest of SE Asia around 1st cent. CE and from China between the 6th and 17th centuries. The SE Asian lineages have formed a Hīnayāna base for Vietnamese Buddhist practice supporting a superstructure of Chinese Mahāyāna, chiefly Zen (Vietnamese Thiền). The Tha'o-Du'ò'ng lineage, a form of the Chinese Sung Dynasty synthesis imported in the 11th cent., had great influence on the character of Vietnamese Buddhism as a harmony of Zen (emphasizing wisdom) and Pure Land (emphasizing compassion). An indigenous form of Lin-chi (Vietnamese, Lâm-Tề) was founded by Liễu-Quán (d. 1743) and became the dominant lineage. All lineages were merged into the Unified Buddhist Church of Vietnam (Vietnamese, Việt-Nam Phật-Giáo Thống-Nhất Giáo-Hội) in 1963.