The basic 12-bar blues progression forms the structure of not only many blues tunes but of many rock, folk, country and other popular styles as well.

Standard 12-bar progressions consist of only three chords -- The I, or tonic chord, the IV chord and the V chord of whatever key the song happens to be in. You'll recall from your diatonic harmonization series that the I, IV and V chords are the chords that are major in any given key.

Here is a basic 12-bar pattern in G. Note where the chords change:

| G | G | G | G |
| C | C | G | G |
| D | C | G | D7|

Although there are some minor variations that we'll cover a little later, the basis of all 12-bar progressions is 4 bars of the I chord (first 4), 2 bars of the IV chord followed by 2 bars of the I chord (second 4), and lastly 1 bar of the V, one bar of the IV, one bar of the I, and one bar of the V (last 4). The last V chord functions as the turn-around, and is often a dominant 7 chord.

In our example above, the chords are G, C and D, with a D7 thrown in for bar 12. Practice the example once using open position chords, and once using bar chords.

Naturally, this progression can be transposed to any key, but the most common keys for guitar are E, G, D, A, C and sometimes B. Here's the I, IV and V for each key:

Note that a lot of these are chords are common open-position chords. Play the progression in each key, and once again use both chord types.

All of the above examples are MAJOR blues. You can solo over these using either the major pentatonic scale, or (oddly enough) the minor pentatonic scale for each key. You would think that the major third in the tonic chord would really clash with the minor third in the minor pentatonic, and you'd be right, but that's the blues for ya! In practice, that minor third is actually pulled sharp a little bit so that it's actually somewhere between the minor and major third. Some scholarly types even call this a separate "blue" scale instead of a minor pentatonic.

Minor 12-bar blues progressions often follow the same pattern, but instead of using the I, IV and V, they use the vi, ii and iii. Once again referring to the lesson on diatonic triad harmonization, you'll see that these are the minor chords of any given key. Starting on the sixth degree of may initially seem strange, but if you study the progression for a while you'll see that the interval relation ship for vi-ii-iii is the same as I-IV-V. (There are often some significant differences in minor blues progressions, but that's another lesson.)

We've also just discovered our first application of the concept of relative minors. The sixth degree of any major scale is the first degree of that major key's relative minor key. A major key and it's relative minor have the same key signature, and therefore the same notes, so you can't really tell if a particular song is major or minor just by looking at the key signature. The difference is the tonal center of the piece.

Here's an example given by Raymond Elliot in his book, Fundamentals of Music, (published by Prentice-Hall). His example is the Christmas carol We Three Kings. This piece is in the key of Eminor/Gmajor (i.e., same key signature).

It kicks off with the three kings whining about how far they've travelled through the desert, so the first part is in E minor for that plaintive, sad character that minor keys have. The tonal center is E. Then, at the chorus, when they're singing about the joyful promise that the star is leading them toward, the melody switches to the the happy-sounding relative major, which is G. And this is about the most familiar and succinct explanation of relative minor/majors that I've run across.

A more contemporary example of the same idea is Mr. Jones by Counting Crows. Same deal, minor in verse, relative major in chorus.
©1996 Dennis W. Fohringer