Understanding Chord-Scale Theory
Chord-scale theory is a systematic approach to jazz improvisation that pairs specific scales with chord types. Rather than thinking of harmony and melody as separate entities, this method recognizes that chords and scales are two expressions of the same harmonic concept—chords are vertical (notes stacked), while scales are horizontal (notes in sequence).
This syllabus organizes scales by their parent chord quality, making it easy to find appropriate scale choices for any chord you encounter. When you see a chord symbol on a lead sheet, you can quickly identify which scales will work based on the chord's fundamental quality.
How to Use This Syllabus
Start by selecting a chord quality from the five categories: Major 7, Dominant 7, Minor 7, Half-Diminished, or Diminished 7. Each quality shows multiple scale options ranging from the most common (like Mixolydian for dominant chords) to more colorful alternatives (like Altered or Lydian Dominant). Use the transpose feature to see the actual notes in any key—this is especially helpful when practicing in all 12 keys or preparing for a specific tune.
The Five Chord Quality Categories
Major 7 (Δ7) chords have a bright, stable quality. Ionian (major scale) is the default, but Lydian adds a raised 4th for extra brightness, making it the preferred choice for many jazz pianists on tonic major chords.
Dominant 7 chords are the most versatile, accepting the widest variety of scales. Mixolydian is the basic choice, but the altered scale, Lydian dominant, diminished, and whole tone all create different colors. Your choice depends on whether the chord is functioning as a V7 in a ii-V-I, or as a more static blues-based chord.
Minor 7 (-7) chords can use Dorian, Aeolian, or Phrygian depending on context. Dorian is the jazz default (its raised 6th avoids clashing with the major 6th often added to minor chords), while Aeolian suits a more classical or folk sound.
Half-Diminished (ø7) chords typically function as ii chords in minor keys. Locrian ♯2 is the preferred choice because it raises the 2nd degree, making the scale more melodic than pure Locrian.
Diminished 7 (°7) chords use the symmetrical diminished scale, which alternates half and whole steps. This creates an 8-note scale with interesting harmonic possibilities.
Scale Selection Principles
- Harmonic context matters: A Dm7 as the ii in a ii-V-I sounds best with Dorian, while the same chord in a modal tune might use Aeolian or Phrygian.
- Voice leading considerations: Choose scales that create smooth melodic lines into the next chord. The altered scale on a V7 chord contains notes that resolve beautifully to the I chord.
- Avoid notes: Some scale degrees clash with chord tones. The 4th on a major chord, for example, is typically treated as a passing tone, not a resting point.
- Inside vs. outside: More common scales sound "inside" the harmony, while exotic scales create tension and sound "outside." Master the inside sounds first.
Practice Strategies
Don't just memorize scales—practice applying them musically. Here are effective approaches:
- Play each scale over a static chord vamp, listening to how each note sounds against the harmony.
- Practice ii-V-I progressions in all 12 keys, using appropriate scales for each chord.
- Transcribe solos by jazz masters and analyze which scales they choose for each chord.
- Limit yourself to one scale per practice session and explore its melodic possibilities thoroughly.
- Use the play buttons to hear the scales, then sing or play along to internalize the sounds.
Beyond the Basics
Once you've mastered the common scale choices, explore superimposition (playing scales from substitute chords), pentatonic applications (5-note scales that outline specific chord colors), and digital patterns (systematic ways of organizing scale tones into memorable phrases). The goal is not to play scales up and down, but to use scale knowledge as a framework for creating musical, expressive improvisations.
Remember: the best improvisers don't think about scales while playing—they've internalized these sounds so thoroughly that they can focus entirely on making music. This syllabus is a map to help you reach that destination.