Unlocking the Mysteries of Diatonic Harmony

Diatonic Harmony – A Game of Chance?

Do you feel like your understanding of diatonic harmony is missing something? On one hand, it makes sense. I mean, heck, it’s only seven chords… right? On the other hand, some composers seem to be able to take those chords and do incredible things with them, while you still plunk out “Louie, Louie.” It’s like gambling.

Learn the Equivalent of Diatonic Card Counting…

With seven simple chords, you’ll be able to explain about 95% of all music written (not a researched number, just go with it). A solid understanding of diatonic harmony will allow you to explain and write chord progressions. It will also give you the ability to venture into chromatic harmony without much effort. It all starts with a few simple concepts.

The Two Ways of Harmony (sounds very zen, doesn’t it…)

There are two ways of using harmony. The first way is luck. It is an accident. Sometimes you get awesome sounding music by just playing around. Unfortunately, implied in the name, it’s hard to duplicate. It’s luck. Sometimes you end up with a good chord progression, and sometimes you don’t. This is how most people start, and sadly, where most people stop. They believe harmony to be a confusing subject. The theory books are all too dry and hard to follow.

The key is to bring in the second way of thinking about harmony.

The Better Way – Functional Harmony

Functional Harmony is a way of thinking about the purpose of chords – both in relation to each other, and to a main harmony. In tonal music, we usually have a note, that is more stable than the others. This is the home key or tonic. Functional harmony gives us a way of moving to and from tonic, in an orderly fashion. To start off our discussion, we will look at functional harmony first in the realm of diatonic harmony. After that we’ll talk about some chromatic harmony. A lot of these ideas come from two books. Classical Form by William Caplin, and A Geometry of Music by Dimitri Tymoczko. I highly recommend both books.

Diatonic Harmony

I am a huge fan of Romantic music. I love the way it winds in and out, with extended chromatic passages and dramatic dynamics. But to understand this type of music, you need a firm grasp on the simpler, diatonic harmony. So what am I talking about when I say diatonic harmony?

Two Scales – Major and Minor

Most music is based off of two tonalities. Major and minor. I don’t feel that a history lesson is all that necessary right now, so I am going to ignore other modes like phrygian, locrian and mixolydian.

Notice the locations of whole steps and half-steps in the scales. This is what gives them their unique tonality.



When we talk about diatonic harmony, we are talking about the harmonies built off of each scale degree in thirds. We have mainly two different types of chords – triads and seventh chords.

When you stack chords on all of the notes, you get the diatonic harmony of that scale. For now, we aren’t going to worry too much about 7th chords, except for the dominant 7th, which is the most common 7th chord.

The Different Ways of Being Minor

One word about minor diatonic harmony. We tends to use most commonly three different types of minor scales in tonal music – harmonic minor, melodic minor and natural minor (relative minor). The one we are really concerned with right now is the harmonic minor scale, which has a minor 3rd scale degree, a minor 6th scale degree and a raised 7th scale degree. Listen to the difference between the three scales.

Harmonic Minor Scale

Melodic Minor Scale

Natural Minor Scale

The harmonic minor scale is used most often for harmony – hence the name. This is because the raised leading tone allows us to have a major dominant 7th chord.

Melodic minor and natural minor are used most often in the melody. In the harmonic minor, there is an augmented 2nd between the 6th and 7th tones. This frequently gives the melody an uneven, stilted feeling. Good if you want to write something middle eastern sounding. Bad if you want to write like Mozart or Beethoven. The melodic minor and natural minor get rid of this by either raising both the 6th and 7th or lowering them.

Major, Minor and Dimished

The chords in diatonic harmony only come in a few different flavors. Major, minor and dimished.

In major diatonic harmony, the chords are:

  • I – Major
  • ii – minor
  • iii – minor
  • IV – Major
  • V – Major
  • vi – minor
  • vii – diminished
In minor diatonic harmony, the chords are:
  • i – minor
  • ii – diminished
  • III – Major
  • iv – minor
  • V – Major
  • VI – Major
  • vii – diminished
You can pick up on a few things from this.
  1. The Major chords are written in capitals, minor chords and diminished in lowercase. You also frequently see M for major and m for minor.
  2. The tonality for the most part flip flops for the scales. I becomes iiii becomes III, vi becomes VI. V and vii don’t really change, and that is because the of the leading tone remaining a half step above. It is also important to to point out that the III uses a lowered 7th tone, also known as the sub-tonic.

Functional Harmony Explained

On to the good stuff. When you first look at the chords that comprise diatonic harmony they don’t mean much. Just a bunch of letters and numbers. But most of them serve specific functions. These functions, just like formal functions, move you along in the harmonic scheme of the music.

The primary harmonic functions are Tonic Function, Dominant Function and Pre-Dominant Function. To help visualize this, we’ll start filling in a chart, that puts everything into clear order. This chart was designed by Dimitri Tymoczko for his book, A Geometry of Music: Harmony and Counterpoint in the Extended Common Practice (Oxford Studies in Music Theory). An excellent book, and I recommend it to anyone.

Tonic Function

Based off of the name, you can probably guess that the tonic function is fulfilled mostly by the chord built off of the first scale degree.

Tonic serves as “home base” for tonal music. It is both where tonal music starts, and where the music ends. It may not end on the same tonic as it started… but it will end on a tonic.

In addition, the chord built on the 6th scale degree can also serve the tonic function in certain cases. This is not so apparent by it’s name, sub-mediant. Let’s add these both to the chart.

Dominant Function

The dominant function is represented by a chord built off of the fifth scale degree. Hence the name dominant. But like tonic, it also has another chord that can function in the same way – the diminished vii.

The purpose of the dominant function is to create harmonic instability and at the same time, confirm the tonic. It does this mainly through the use of the leading tone (7th scale degree) moving to tonic (1st scale degree). Sometimes the diminished vii is not a dominant function is certain diatonic sequences, which we will talk about later.

One more thing, the diminished 7th is usually found in first inversion. An inversion is just taking the note on the bottom, and moving it up to the top. For triads there are two inversions and for 7th chords there are three. These are annotated with little numbers to the side of the harmony, called figured bass. I won’t go into too much detail about figured bass for now, this is not a post about part writing.

Pre-Dominant Function

The purpose of the last function, pre-dominant, is to prepare the dominant. It leads us to the dominant. In diatonic harmony, this is represented by the ii chord and the IV chord.

Pre-dominant functions are usually built directly off of the 4th scale degree. This would leave most people to believe that IV is the most common pre-dominant harmony. But ii in first inversion (ii6) is actually more common.

So how do we use this chart? Follow these simple guidelines:

  • You can always move rightward from one chord to another by any amount.
  • Chords can move leftwards only along the arrows.
  • When I moves to vi and back to I, it is normally to a I6.
  • The short dash lines represent common neighbor and passing chords for tonic. They usually move back to I.
  • vii6 also usually moves back to I, either as a neighbor chord, or as a dominant function.
Listen to this example. The first chord progression just runs straight through the chart. The following chord progressions just remove chords, I don’t add any. It shows you the power of this simple chart. This is not by any means all you can do, just a short example.
What is really cool about this chart, is that is works pretty much the same way in minor.

Introducing Chromatic Harmony

I promised some chromatic harmony, so here it is. The most common types of basic chromatic harmony are pre-dominant functions, either built off of the dominant of the dominant or the 4th scale degree. What does that mean?

Who’s Dominating Who?

Think of it like this. If tonic is C, then it’s dominant is G. Well, if G were the scale being used, it too would have a dominant, which would be D. This is a very common and strong harmony, but is really effective. The reason is because it raises that 4th scale degree, in this case F, to F#. It really makes it want to move to the dominant harmony. Listen to the difference of a ii-V-I progression, and a V/V-V-I progression.

The next type of common chromatic harmony is also pre-dominant, this time using something called modal mixture.

Modal Mixture

Modal mixture sounds mysterious, but it really isn’t. It’s basically just mixing the harmony from the major scale and the minor scale. A very common one is called the Neapolitan 6th. It is a ♭II6 chord. It has a really cool sound. Listen to the example.

That covers a lot of diatonic harmony, but there is still more. We haven’t even talked yet about the types of harmonic progressions. That will have to wait for another day, this article is getting pretty long.


The best thing you can do to really learn diatonic harmony is use the chart to experiment. Find out what sounds good and what doesn’t. Try out different inversions, and look for them in the compositions of the masters. Also try experimenting with modal mixture. That’s where it really starts to get interesting.

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  • Rudiffus

    I have never had the time or money to take real music theory lessons making my search for this imformation very difficult before I read this post. I feel like I have a much better grasp now because of that chart!

    • Jon

      Thanks. Most music theory tends to complicate things… not because its necessarily wrong (or right for that matter) but just because its written so confusing. I am just trying to untangle the ideas, and put them down in as clear a way as possible.

  • Corazon

    Your explanations gave me a clearer grasp of those things. You’re great !!! Thanks

    • http://www.artofcomposing.com Jon

      Glad I could help.

  • Jason

    Awesome! very well explained.

    • http://www.artofcomposing.com Jon

      Thank you very much.

  • http://www.lesliesanford.com Les

    Thank you for your excellent website. I discovered it through your YouTube videos.

    I have a question. I noticed in Dimitri Tymoczko’s chart that the iii is missing. Does the iii chord have a function?

    • http://www.artofcomposing.com Jon

      iii actually doesn’t have it’s own function, but it can prolong tonic.

      • Roula

        According to Riemann, it can also replace the Dominant in some instances, although rarely used.

  • Steve

    Thanks Jon. The chart is good; however I always thought the chord on III in the harmonic minor was augmented (to take account of the sharp 7th)? eg in A minor, III would be C-E-G# = Caug.

    Thanks for the course – loved it!

    • http://www.artofcomposing.com Jon

      Augmented chords are really looked at as modified major or minor triads. In most cases, when you see a III in minor, it is a major chord. Glad to hear you liked the course.


  • André (french)

    thank you for all jon but I find it hard to understand the numbers at the top of the table( to VI,IV6 or iv6) could explain

    thank you again


    • http://www.artofcomposing.com Jon

      Thank you very much.