Baptism for the dead is a distinctive ordinance of the Church of Jesus Christ of Latter-day Saints, in which a living person is baptised by immersion on behalf of a specific deceased individual, standing in as their proxy. The practice rests on the belief that baptism is necessary for salvation, that many have died without the opportunity to receive it, and that a just and merciful God has provided a way for the dead to receive the ordinance vicariously through the living. The deceased, it is taught, retain their agency in the spirit world and may accept or reject the baptism performed on their behalf, so that the rite offers rather than imposes. The practice is the principal reason for the extensive genealogical work for which the church is well known, undertaken to identify the ancestors and others for whom the ordinances may be performed, and it is carried out in the church's temples.
Latter-day Saints ground the practice scripturally in a passage of the Apostle Paul that refers, in passing and without explanation, to people being "baptised for the dead", a verse whose meaning is disputed and which most other Christian traditions do not read as endorsing the practice. Other churches generally reject vicarious baptism as without warrant and contrary to their understanding of the sacrament, and the practice has at times caused friction, notably over the posthumous baptism by proxy of persons from other faiths, including Holocaust victims, which drew objections that led the church to place restrictions on whose names members may submit.