"One of Us Must Know (Sooner or Later)" is a song written and recorded by Bob Dylan. It is the fourth track on his 1966 album Blonde on Blonde, and was released as the album's first single that February. The song is an emotional confession of misconnects and apologies from the singer to a young woman he regrets having mistreated. As a single, it peaked at No. 33 in the UK Singles Chart, but only reached No. 119 on US Billboard's Bubbling Under chart.