This is a lesson of mine that I put together a long time ago for someone on one of the forums...I thought it might be beneficial here.

The question here was posed by "alex" about why certain chords outside the natural diatonic hamony within a key are possible, why they don't sound "wrong"...

Here is the lesson that takes you through chordal function from the beginning. His question is more or less addressed down the line a ways. Keep in mind that his song/example was in "F", but mine (already written) is in "C".

Chord Functions, Diatonic Triad over Bass usage, Non-diatonic Chords, Lyric Writing, Song Form…

What you write first depends on your own process...sometimes lyrics can come first, or a melody...you can find some cools chords and go from there as well...

I do think it would help to have a basic understanding of chord functions...

(I'll assume you know the basics of how chords are built...)

The first step would be to learn the Major/minor diatonic chord functions as such:

(Let's think in the key of C, for example)

I - ii - iii - IV - V - vi - vii
C Dm Em F G Am Bm7b5

Then, think of the scale degrees in natural numbers...

1 2 3 4 5 6 7

(a side note about the vii chord: though theoretically correct as a min7b5 chord...for the purposes of popular harmony put in it's place the V chord, but with the 7th degree of the scale in it's place...)

So, it would be written as such: G/B or in numbers: V/7

(if you're familiar, the "Nashville Numbers System" is a little different, but I want to differentiate between "chord" and "scale degrees" for our purposes)

Then, group them in sets of two in every possible combination:

I – ii
I - iii
I - IV
I - V
I - vi
I - vii

ii - I
ii - iii
ii - IV
ii - V
ii - vi
ii - vii

iii - I
iii - ii
iii - IV
iii - V
iii - vi
iii - vii

IV - I
IV - ii
IV - iii
IV - V
IV - vi
IV - vii

V - I
V - ii
V - iii
V - IV
V - vi
V - vii

vi - I
vi - ii
vi - iii
vi - IV
vi - V
vi - vii

vii - I
vii - ii
vii - iii
vii - IV
vii - V
vii - vi

Ok, now what to do next...

Take these sets of two chords and play them on your instrument repeatedly...

So, you would play: I - ii, I - ii, I - ii; over and over again...(the purpose of which, would be to drill the sound of it in your head...)

Do this with each two-chord set...

This will instill an inner sense of the sound of any chord function to any other chord function...

The following would be helpful...

Know that the stronger chord moves are:

I - IV
IV - I
I - V
V - I

Know that a common strong progression is:

I - IV - V


I - vi - IV - V

I - vi - ii - V


ii - V - I

IV - V - I

iii - vi - ii - V - I


Now take two, two-chord sets: say, I - IV and vi - V...combine them, play them, become familiar...do this with each set...it will train your ear to hear chords in progression form...without having to "know" deeper theory to begin this process...


Take every chord in the key and place in the lowest point in the chord, any other scale degree toproduce the "slash" chords...

For example:

I/2, I/3, I/4, I/5, I/6, I/7
C/D, C/E, C/F, C/G, C/A, C/B

Do this with every chord and scale degree to find all of the possibilities...

Keep in mind, that so far, I have only given chordal information. MELODY (and a strong one with a hook, at that) is the key to creating a memorable song...

However, if you begin with a good foundation of chord theory, melody can come easier... (also, if you have a melody in your head, you can write chords to it, giving it a harmonic structure)...

I'll stick with the chordal information for now...

Now, the next step is to begin experimenting with those "slash" chords (named for the "/" used in the chord symbol---nothing to do with the
G-n-R guitarist) within your exploration of the chord progressions, built from the two-chord sets...

In other words...

Take the progression:
I - IV - vi - V or C - F - Am - G

and use the slash chord concept as such:

I/3 - IV - vi - V/7 or C/E - F - Am - G/B

Now, we'll look at the minor sound, briefly...

Every Major Key has what is known as a relative minor key...

First fact: it is ALWAYS the 'vi' chord of that Major key...ALWAYS.

For C Major, it's relative minor key is A minor

C - Dm - Em - F - G - Am - (G/B)

I - ii - iii -IV- V - vi - (V/7)

It means simply that within the chords already in place in the Major key, there exists an entirely different minor key...

You change nothing except the FUNCTION of each chord...

In other words, you'll simply shift the Roman Numeral functions to make the Am, the first chord, etc...

As such,

Am - G/B - C - Dm - Em - F - G

i - VII/2 - III - iv - v - VI - VII

Now, something CAN change slightly with the 'v' chord...

Generally, a fifth degree chord is a dominant 7th chord (I'll get into 7th chords another time...just nod and smile...)

So, the fifth degree chord in Am would be a better approach as E7, instead of Em...

This will lead into the next concept so stay alert...


So, really there are many combinations already, to choose from, just by playing through these relatively simple exercises...

All diatonic two-chord combinations, four-chord combinations, and the use of "slash" chords...and now the relative minor key...

Now let's look at using non-diatonic chords (chords not in the key)...

Look first, briefly, back to the key of 'C' :

C - Dm - Em - F - G - Am - (G/B)

I - ii - iii -IV- V - vi - (V/7)

(---remember we're substituting the V/7 chord for the theoretically correct m7b5, because for popular music, it's a cleaner sound, serving the same purpose...)

Ok, the the thing to look at is the V chord...

The V of 'C' is G...

Now look at each chord in the key of 'C'

Just consider that EVERY chord, apart from any function in any key, is it's very own 'I' chord (Major) or 'i' chord (minor) in it's very own key somewhere...

For example, though Dm is the 'ii' chord of C Major, it is also the 'vi' chord of F Major...

I'll take a huge leap here and just jump to what you can use...

So, with that in mind...

Think these chord relationships (typically referred to as secondary dominants):

*note that the slash chords are that chord with it's 3rd degree in it's root.

V of C is G or G/B

V of Dm is A or A/C#

V of Em is B or B/D#

V of F is C or C/E

V of G is D or D/F#

V of Am is E or E/G#

So, how this can be used is this:

Say you are playing from these chords to chords:

C to Dm

try approaching the chord as you ascend with it's V chord:

C to A/C# to Dm

Do the whole key:

C (A/C#) Dm (B/D#) Em (C/E) F (D/F#) G (E/G#) Am (*) G/B

(*there is no approach to the seventh chord because it is already derived from a 'V' chord)


This is the first step in finding non-diatonic chords...

Next, we'll look at substituting chords in the place of
the 6th and 7th degree chords...

A simple way to do this is to first look at the original chords:

C - Dm - Em - F - G - Am - (G/B)

I - ii - iii -IV- V - vi - (V/7)

And look at these substitutions:

...in place of Am, drop it down a half-step and make it an Ab Major chord

...in place of G/B, drop it down a half-step and make it an Bb Major chord

Some possible progressions:

C - F - Bb - C

C - F - Ab - Bb - C


Now, look at the other minor chords and do the same...

...in place of Em, drop it down a half-step and make it an Eb Major chord

...in place of Dm, drop it down a half-step and make it an Db Major chord

Some possible progressions:

(utilizing the others as well)

C - F - Eb - Bb - C

C - Bb- Eb - F - C - Bb - Ab - Db - C

Use slash chords by simply putting the 3rd of each chord in the root:

C - Bb/D - Eb - F/A - C - Bb - Ab/C - Db/F - C/E

Just a random progression really, but it gives you an idea of how it might sound to experiment with this exercise...

To address the use of using the IV chord as a minor chord:

The reason this works is that it is related to other chords with modulative properties:

in "C"

Am6 is common to Bb9(b5), which is common to E7b5(b9), which is an altered V chord of the iv chord the relative minor of the tonic "C"

in "F"

Bbm6 is common to Eb9(b5), which is common to A7b5(b9), which is an altered V chord of the iv chord the relative minor of the tonic "F".

Bbm6 also has properties related to the V altered chord, C7(b9) of the tonic, F.

So the inner ear hears the connection. You can use the progression "Fmaj7, Eb9, Dm7, A7b5(b9), Gm7, Bbm6, Fmaj7.

Obviously, this information isn't going to guarantee anything...but it should help your process...