"(What's So Funny 'Bout) Peace, Love, and Understanding" was written by Nick Lowe in 1974. The original version with his group Brinsley Schwarz was kind of somber, but Elvis Costello made it a classic with his 1978 uptempo take.
The lyrics for "Mary, Did You Know?" were written by Christian singer and comedian Mark Lowry, after his pastor asked him to write a Christmas musical for their church. Southern gospel musician Buddy Greene later added music to his words.