Chords in A Mixolydian

A Mixolydian is built from the notes A, B, C#, D, E, F# and G. Its scale carries 2 sharps. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on A as the I. The chord on the fifth degree is Em rather than a major V, so A Mixolydian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain A minor.

Beyond those seven, A Mixolydian commonly borrows Am (i), Bdim (iiø), C (bIII), Dm (iv) and F (bVI) from the parallel minor — the mixture chords that give a progression somewhere unexpected to go.