The band uses bluegrass and folk instrumentation, such as a banjo, upright bass, mandolin and piano, played with a rhythmic style based in alternative rock and folk. Much of Mumford & Sons' lyrical content has a strong literary influence, its debut album name deriving from William Shakespeare's Much Ado About Nothing. The track "Sigh No More" includes lines from the play such as Serve God love me and mend, For man is a giddy thing, and One foot in sea and one on shore. The song "Roll Away Your Stone,"'s title alludes to Macbeth; the song includes the line Stars hide your fires/And these here are my desires which borrows and pares down Macbeth's line in Act 1 Scene 4:Stars, hide your fires,/Let not light see my black and deep desires. In an interview, Mumford was quoted as saying, "You can rip off Shakespeare all you like; no lawyer's going to call you up on that one."

Additionally, "The Cave" includes several references to The Odyssey, in particular the sirens that Odysseus encounters on his journey home. The song also contains many references to G.K. Chesterton's book, St. Francis of Assisi, in which Chesterton uses Plato's Cave as a way of explaining how St. Francis views the world from God's perspective. In addition, the song "Little Lion Man" appears to be a retelling in dramatic monologue form of Chretien de Troyes' Yvain, the Knight of the Lion, which is the story of a knight who goes mad after betraying a promise to his wife to return to her.