Nine Lessons and Carols, also known as the Festival of Nine Lessons and Carols and Service of Nine Lessons and Carols, is a service of Christian worship traditionally celebrated on or near Christmas Eve in Anglican churches. The story of the fall of humanity, the promise of the Messiah, and the birth of Jesus is told in nine short Bible readings or lessons from Genesis, the prophetic books and the Gospels, interspersed with the singing of Christmas carols, hymns and choir anthems.

Although the tradition of Nine Lessons and Carols is popularly associated with King's College, Cambridge, its origins are attributed to Truro Cathedral in Cornwall. Up to the late 19th century, the singing of Christmas carols was normally performed by singers visiting people's houses, and carols — generally considered to be secular in content — had been excluded from Christian worship. In the Victorian era, the rising popularity of hymnody encouraged church musicians to introduce carols into worship. An 1875 book of carols, Carols for Use in Church During Christmas and Epiphany by Richard Chope and Sabine Baring-Gould, was an influential publication. At around this time, the composer and organist John Stainer was compiling a collection, Christmas Carols New and Old, and during Christmas 1878 he introduced carols into the service of Choral Evensong at St Paul's Cathedral in London. Other cathedrals also began to adopt carols at Christmastide that year and the Royal Cornwall Gazette reported that the choir of Truro Cathedral would sing a service of carols at 10:00 pm on Christmas Eve:

The Choir of the Cathedral will sing a number of carols in the Cathedral on Christmas Eve, the service commencing at 10pm. We understand that this is at the wish of many of the leading parishioners and others. A like service has been instituted in other cathedral and large towns, and has been much appreciated. It is the intention of the choir to no longer continue the custom of singing carols at the residences of members of the congregation.

— Royal Cornwall Gazette, 20 December 1878

Two years later, the Right Rev. Edward White Benson, at that time Bishop of Truro, conducted the first formal service of "Nine Lessons and Carols" on Christmas Eve (24 December) 1880. Benson, concerned at the excessive consumption of alcohol in Cornish pubs during the festive season, sought a means of attracting revellers out of the pubs and into church by offering a religious celebration of Christmas. The idea for a service consisting of Christmas music interspersed with Bible readings was proposed by the succentor of the cathedral, the Rev. George Walpole (who later became Bishop of Edinburgh). The cathedral — a Victorian gothic building — was still under construction, and services were being held in a temporary wooden structure which served as a pro-cathedral. The first Nine Lessons and Carols service took place there at 10:00 p.m. on Christmas Eve and was attended by over 400 people.

Benson's son, A. C. Benson, later recalled:

My father arranged from ancient sources a little services for Christmas Eve, nine carols and nine tiny lessons. They were read by various officers of the church, beginning with a chorister and ending, through different grades, with the bishop.

— A. C. Benson,