In some schools of Buddhism, bardo (Classical Tibetan: བར་དོ་ Wylie: bar do) or antarābhava (Sanskrit, Chinese and Japanese: 中有, romanized in Chinese as zhōng yǒu and in Japanese as chū'u) is an intermediate, transitional, or liminal state between death and rebirth. The concept arose soon after Gautama Buddha's death, with a number of earlier Buddhist schools accepting the existence of such an intermediate state, while other schools rejected it. That is to say that during the so-called third Council in Pataliputra (Patna) the Asokan section of early Buddhism rejected this concept of àntāra-bháva. Some of those monks who, during this Council, were disrobed and sent away re-introduced it in Hybrid Sanskrit manuscripts. Franklin D. Edgerton mentions àntarābhávika in the Bodhisatttva-bhumi: "someone living in the intermediate state", and àntarābháva in the Làlita-vistára and Abhidhárma-kosa.

The concept of antarābhava was brought into Buddhism from the Vedic-Upanishadic (later Hindu) philosophical tradition. Later Buddhism expanded the bardo concept to six or more states of consciousness covering every stage of life and death. In Tibetan Buddhism, bardo is the central theme of the Bardo Thodol (literally Liberation Through Hearing During the Intermediate State), the Tibetan Book of the Dead, a text intended to both guide the recently deceased person through the death bardo to gain a better rebirth and also to help their loved ones with the grieving process.

Used without qualification, "bardo" is the state of existence intermediate between two lives on earth. According to Tibetan tradition, after death and before one's next birth, when one's consciousness is not connected with a physical body, one experiences a variety of phenomena. These usually follow a particular sequence of degeneration from, just after death, the clearest experiences of reality of which one is spiritually capable, and then proceeding to terrifying hallucinations that arise from the impulses of one's previous unskillful actions. For the prepared and appropriately trained individuals, the bardo offers a state of great opportunity for liberation, since transcendental insight may arise with the direct experience of reality; for others, it can become a place of danger as the karmically created hallucinations can impel one into a less than desirable rebirth.

Metaphorically, bardo can be used to describe times when the usual way of life becomes suspended, as, for example, during a period of illness or during a meditation retreat. Such times can prove fruitful for spiritual progress because external constraints diminish. However, they can also present challenges because our less skillful impulses may come to the foreground, just as in the sidpa bardo.

From the records of early Buddhist schools, it appears that at least six different groups accepted the notion of an intermediate existence (antarabhāva), namely, the Sarvāstivāda, Darṣṭāntika, Vātsīputrīyas, Saṃmitīya, Pūrvaśaila and late Mahīśāsaka. The first four of these are closely related schools. Opposing them were the Mahāsāṃghika, early Mahīśāsaka, Theravāda, Vibhajyavāda and the Śāriputrābhidharma (possibly Dharmagupta).

Some of the earliest references to an "intermediate existence" are to be found in the Sarvāstivādin text the Mahāvibhāṣa (阿毘達磨大毘婆沙論). For instance, the Mahāvibhāṣa indicates a "basic existence" (本有), an "intermediate existence" (中有), a "birth existence" (生有) and a "death existence" (死有) (CBETA, T27, no. 1545, p. 959, etc.). André Bareau's Les sectes bouddhiques du Petit Véhicule provides the arguments of the Sarvāstivāda schools as follows:

The intermediate being who makes the passage in this way from one existence to the next is formed, like every living being, of the five aggregates (skandha). His existence is demonstrated by the fact that it cannot have any discontinuity in time and space between the place and moment of death and those of rebirth, and therefore it must be that the two existences belonging to the same series are linked in time and space by an intermediate stage. The intermediate being is the Gandharva, the presence of which is as necessary at conception as the fecundity and union of the parents. Furthermore, the Antarāparinirvāyin is an Anāgamin who obtains parinirvāṇa during the intermediary existence. As for the heinous criminal guilty of one of the five crimes without interval (ānantarya), he passes in quite the same way by an intermediate existence at the end of which he is reborn necessarily in hell.

Deriving from a later period of the same school, though with some differences, Vasubandhu's Abhidharmakośa explains (English trs. p. 383ff):