The last of the essential concepts to understand is how to choose a mode that fits with an entire chord progression. Be aware, of course, that there can be (and often are) situations where a single mode simply does not work with a chord progression, and you have to switch modes at certain points to accommodate the chord of the moment. In many cases, though, you can just apply one mode to a sequence of chords and just let ‘er rip. This is fairly common in the Grateful Dead/Phish/jamband universe, where modal jams are par for the course.

I have to add that the #1 most important thing is to LISTEN to how your melodies sound in relation to the chords.  Sometimes it seems (on paper) that you can apply more than one mode to a chord progression, so you just have to decide by LISTENING which you think sounds the best for the situation. It takes some trial and error, but after a while you’ll get better at it.

It’s also worth noting that mode-based improvisation is something that is very common in the jamband world, but less common in straight-ahead rock (which tends to be more blues-based), country/bluegrass (which tends to be based more on licks over given chords), and jazz (which tends to have many different chords and even key centers within a given improvisation).

Where is home?

The first thing to figure out is what the “home” chord is. This is the chord that all of the chords in a given song/progression sound like they want to return to. It’s not always 100% obvious, but one fairly reliable way to determine this is to think about what chord you would end the song on. Is that chord major? That narrows it down to ionian, lydian, or mixolydian. If the chord is minor, then it must be dorian, aeolian, or locrian.

Some modes more common than others

You can also simply play the odds, to some extent. Based on my own personal experience in the classic rock and jamband worlds, I would say that this is how the modes rank in terms of how often they appear in improvising situations:

Major:

1. Mixolydian: Very common in the Grateful Dead and Phish worlds for major key jams like “Dark Star” and “Bathtub Gin”.
2. Ionian: Often found in the folkier music of Garcia & the Dead such as “Friend of the Devil” and “Peggy-O”, also notably in “Eyes of the World,” and on the Phish side in “Harry Hood”.
3. Lydian: Not super common, but on the Phish side, it does appear in “Reba,” “Wingsuit,” and the “With” jam of “The Curtain (with).” On the Dead side, it appears in “Lady with a Fan” and 80’s versions of “Cassidy”. Often also favored by guitar shredders like Joe Satriani and Frank Zappa.

Minor:

1. Dorian: The most common minor key mode for funk/rock/jazz jams like “Whippin’ Post” and “Oye Como Va.”
2. Aeolian: A darker sound that is not as common, but shows up here and there in songs like “Stairway to Heaven.”
3. Phrygian: Not common, can have a somewhat exotic “Spanish” kind of sound.

And as I have said elsewhere, the locrian mode basically never appears anywhere.

Chord Scales Contain Clues

At this point I strongly recommend returning to the lesson on chord scales, as well as the table of major scales, to make sure you understand them. But to briefly re-iterate, the chord scale of any major key is as follows:

I=major, II=minor, III=minor, IV=major, V=major, VI=minor, VII=diminished

A couple things in particular that I will point out: There is only one place within the chord scale where two major chords appear a whole step apart–the 4th & 5th degrees. So if you see a C and a D chord in the same progressions, they MUST be the 4th and 5th of their chord scale. The same would be true of two minor chords a whole step apart–the would have to be the 2nd and 3rd degrees of their chord scale.

Obvious and Common Choices

While there are lots of different possible chord progressions that could dictate a certain mode, the truth is that in actual practice, there are a few progressions that typically show up to indicate a certain mode. Here’s a rundown of the most common:

Ionian

The ionian mode is likely to be your best choice if you see:

• A progression comprised strictly (or even mostly) of the I, IV, and V chords of a key.
• A progression that goes something like I (major) > II (minor) > III (minor) Examples of this include “Melissa” by the Allman Brothers and “I Shall Be Released” by The Band/Bob Dylan.

Dorian

The dorian mode is the most common mode for improvising in minor keys. It has a couple of common applications:

• When the progression starts on a minor chord and also has a major chord on the 4th degree, such as Am > D (as in “Oye Como Va” or “Elizabeth Reed”), or Em > A (“Down By The River”).
• When the progression starts on a minor chord and is followed by a major chord a whole step down, such as Am > G (note, this could also indicate the aeolian mode, but dorian tends to be more common).

Phrygian

The phrygian mode is not super common, but there’s one big giveaway:

• When the progression starts on a minor chord and is followed by a major chord a half step up, such as F#m > G (“Lost Sailor” by GD) or C#m > D (Zappa’s “Black Napkins”).

Lydian

The lydian mode is probably the least common of the major-chord modes, but it does make some appearances (and, IMO, is a very cool sound). There’s one main giveaway for the lydian mode:

• When the progression starts on a major chord (or maj7) and is followed by another major chord a whole step above, such as Ebmaj7 > F (“The Curtain With” and “Reba” by Phish) or Fmaj7 > G (GD’s “Lady With A Fan”).

Mixolydian

The mixolydian mode is very common for jamming on major chords, and there’s really one primary (almost cliché) context for it.

• When a progression starts on a major chord and continues to another major chord a whole step below, as in B > A (“Fire On The Mountain”) or D > C > G (“Can’t You See,” “Theme From The Bottom”).

Aeolian

There’s also only really one main kind of progression that calls for the aeolian mode.

• When the progression starts on a minor chord, goes to a major chord a whole step down, and then goes to another major chord a whole step down, as in Am > G > F (“Stairway To Heaven”), or Dm > C > Bb (“Sultans of Swing”) or Bm > A > G (“All Along The Watchtower”).

Locrian

The locrian mode is used so infrequently that you don’t even need to worry about it. If for some reason you do end up with a long improvisation on a diminished chord, locrian is an option. But I have literally never seen this.