The Sunday School came to prominence as part of the Nonconformist movement during the nineteenth century.  The core of its activities were weekly classes, but they also included annual trips.  Classes were held for chapel-goers of all ages, although the Sunday School has now come to be seen as primarily for children and young people.

The Sunday School did not originate in Wales; similar classes were held in Italy from the 16th century and Robert Raikes promoted the idea in England in the 18th century.  Griffith Jones of Llanddowror paved the way for the Sunday School movement during the eighteenth century.  Jones's circular schools sought to increase the literacy rate so that people would have the opportunity to read their Bibles for themselves.  However, it is Thomas Charles, a Calvinistic Methodist minister from Bala, who is best known for the promotion of the Sunday School in Wales.

A Welsh Sunday Schools Council was formed in 1966, not because of the continued success of the movement, but because of the need to promote the work through the medium of the Welsh language.  In much the same way as the Sunday School benefited from the strength of the Nonconformist church in the 19th century, it has been affected by the number of chapel-goers across Wales have dwindled over the course of the 20th century.