"One of Us Must Know (Sooner or Later)" is a song written and recorded by Bob Dylan for his 1966 album Blonde on Blonde. It was recorded in late 1965 in New York with members of The Band (then known as The Hawks) included in his backing band. It was one of only two songs to be used from these sessions, along with "Can You Please Crawl Out Your Window?", which was released as a single in 1965. The song is an emotional confession of misconnects and apologies from the singer to a woman who has tragically slipped out of his life. As a single, it reached number 33 in the UK chart.
According to Jonathan Singer, it was Paul Griffin who played the piano part on "One of Us Must Know (Sooner or Later)".
A particularly noteworthy and unusual Phil Spector styled cover of this song was released by Les Fradkin on his "If Your Memory Serves You Well" CD in 2006.