"Billy Boy" is a traditional folk song and nursery rhyme found in the United States, in which "Billy Boy" is asked various questions, and the answers all center on his quest to marry a girl who is said to be too young to leave her mother.
It has a Roud Folk Song Index number of 326. It is a variant of the traditional English folk song "My Boy Billy", collected by Ralph Vaughan Williams and published by him in 1912 as number 232 in Novello's School Songs.