Today I want to cover a topic, that seems so obvious once you see it, that you may wonder why you never saw it before. I suspect every advanced player knows this, but perhaps showing it this way, will help in some way open a new door.

A question I hear all the time is “How do I know what chords go with what key?” On the surface, having this concept mastered, seems like an advanced theory topic … but is it really? The question is: Can you answer this question for yourself, using simple observation? The answer is – yes! So let’s get down to the real reason why chords can be grouped so predictably.

The major scale pattern
Most Western music is based around the major scale. Of course there are other scale harmonies that can be used (melodic minor, harmonic minor etc). But for the sake of simplicity this discussion will center around the major scale. Apply these same principles to any scale to explore its harmony. I recently did an entry on building box patterns that you should read if you are new to this concept (or just need a refresher) it can be found by clicking here.

Assuming that you have read that, and know how to build a major scale; lets look at the first pattern of the major scale (also known as Ionian mode). Take a look at these forms, and join me on the other side!

 
As you can see just by looking there are familiar chord shapes that can be found (highlighted in red) simply by clustering together. OR it can be said that each note has a natural strong connection with other notes of the scale. It is these connections that define the sounds of the chords. Translation: the chords are simply children of the scale. (The shapes I selected above are the ones I thought most people would easily recognize, so understand that there are other ways, perhaps better way of building these chords.) It was huge for me, the day I realized that a G chord wasn’t ONLY played as the first position chord I learned long ago. That chord, or any chord, is just a collection of notes. Those notes found in any order, in any place on the neck, are all equally G chords.
Chord Order
To expand on this, there are certain observations that can be extrapolated. If you look at the type of chord off of each note you will see a pattern of:
I Chord – Major
II Chord – minor
III Chord – minor
IV Chord – Major
V Chord – Major (This is actually commonly a V7 chord)
VI Chord – minor
VII Chord – dim (I have shown the min7b5 as the seventh chord as it is the one I prefer. Classical formal theory calls for a diminished chord, but a half diminished or also named m7b5, will work as well. It is actually equally common in my travels.)
So we can then say that in any major key the chords within will follow this set order:
Major, minor, minor, Major, Major (7), minor, diminished (m7b5)
So for other keys simply: 
– pick note (key) of choice
– apply the major scale formula (as outline in my previous post click here)
– apply the above chord order

Cool! But what comes next?
The best part is; by looking at how the chord is surrounded by the scale tones, you now have the ability to add extension notes to the chords (7’s, 9’s, 13’s). Basically, number the scale: 1 being the root note the next note is 2, then 3 etc. So you want an add9 chord? No problem! Take a chord, count up 9 notes in the scale and ‘add’ it to the chord you are altering. You can add any note from the scale to any of the chords and explore new sounds without leaving the key – remaining diatonic (a fancy word for ‘of the key’)

Another easy way to find common chord shapes, is to select every other note of the scale. This stacking of 3rds process is the building block for creating the chords and the rules generated above. But dont stop at the fifth, extend them out to 7ths, 9ths whatever you like. Extra credit: You are also simultaneously assembling arpeggios for all you lead players. Need a Maj6 arp? Get the paper out and get busy!

So pick away and explore as many new voicings as you can. Apply the same ideas to other patterns of the major scale (Dorian, Phrygian – you know the names). I think you will be surprised by all the new chording ideas you will find. The point of all this is: the information is there for you. Locked inside scales you already know. You just need to apply some observation skills to extract it.

Having some time to practice wouldn’t hurt either!