This is a music book. 'When the Saints Go Marching In', often referred to as 'The Saints', is an American gospel hymn. The precise origins of the song are not known. Though it originated as a Christian hymn, it is often played by jazz bands. This song was first recorded on May 13, 1938 by Louis Armstrong and his Orchestra. The song is sometimes confused with a similarly titled composition "When the Saints are Marching In' from 1896 by Katharine Purvis (lyrics) and James Milton Black (music). Both vocal and instrumental renditions of the song abound. Louis Armstrong was one of the first to make the tune into a nationally known pop tune in the 1930s. Armstrong wrote that his sister told him she thought the secular performance style of the traditional church tune was inappropriate and irreligious. Armstrong was in a New Orleans tradition of turning church numbers into brass band and dance numbers that went back at least to Buddy Bolden's band at the start of the 20th century.