Chords in Ab Mixolydian

Ab Mixolydian is built from the notes Ab, Bb, C, Db, Eb, F and Gb. Its scale carries 5 flats. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Ab as the I. The chord on the fifth degree is Ebm rather than a major V, so Ab Mixolydian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain Ab minor.

Beyond those seven, Ab Mixolydian commonly borrows Abm (i), Bbdim (iiø), Cb (bIII), Dbm (iv) and Fb (bVI) from the parallel minor — the mixture chords that give a progression somewhere unexpected to go.