Guitar chords in the key of Bb major

The seven chords of Bb major are Bb, Cm, Dm, Eb, F, Gm, Adim. Each one has a job in the key, and each tends towards particular chords next.

• Bb, the tonic of Bb major. Usually goes to Eb or F: the first move away from home, and the one that does not raise the stakes.
• Cm, the supertonic of Bb major. Usually goes to F: roots falling a fifth, the strongest root motion the key has.
• Dm, the mediant of Bb major. Usually goes to Gm: roots falling a fifth, and vi is where iii most often lands. It contains the key's leading tone, so it leans towards the tonic.
• Eb, the subdominant of Bb major. Usually goes to F: subdominant into dominant: the standard approach to a cadence.
• F, the dominant of Bb major. Usually goes to Bb: the tritone resolves: the leading tone rises, the seventh falls, and the phrase is over. It contains the key's leading tone, so it leans towards the tonic.
• Gm, the submediant of Bb major. Usually goes to Cm or F: roots falling a fifth, straight into the standard approach to V.
• Adim, the leading-tone chord of Bb major. Usually goes to Bb: it is V7 without its root, so it wants the tonic just as badly. The ♭5 puts a tritone inside the chord itself, so it cannot be sat on: it is heard as tension wherever it stands, and it is used on the way to something rather than as a place to arrive. It holds A and E♭, the tritone out of V7, so it carries the dominant's tension wherever it sits. It contains the key's leading tone, so it leans towards the tonic.

Where a chord tends to go follows Walter Piston’s table of usual root progressions in Harmony (W. W. Norton); see the sources.