Mastering II-V-I from Chord Tones Up — A Guitarist's Guide to Jazz Improvisation
By Masashi Y.
“I know my scales. But when I try to improvise, I just run up and down the scale.”
The root cause is usually the same: not targeting chord tones.
A scale has 7 notes, but only 3–4 of them define the chord’s sound — those are the chord tones. Build your phrases around chord tones, and you’ll break out of aimless scale runs.
This guide uses jazz’s most fundamental progression — II-V-I — to walk through improvisation in three stages: chord tones → scales → tensions.
What Is II-V-I?
II-V-I (two-five-one) is the most common chord progression in jazz. In the key of C major:
| Degree | Chord | Function |
|---|---|---|
| II | Dm7 | Subdominant (preparation) |
| V | G7 | Dominant (tension) |
| I | Cmaj7 | Tonic (resolution) |
The “preparation → tension → resolution” arc means your note choices should follow the same trajectory for maximum musical impact.
Step 1: Play Chord Tones Only
Before scales, start with just the chord tones (R, 3rd, 5th, 7th) of each chord.
Dm7 Chord Tones
Dm7 = D, F, A, C (root, b3, 5, b7). Here’s where they sit on the fretboard:
G7 Chord Tones
G7 = G, B, D, F (root, 3, 5, b7):
Cmaj7 Chord Tones
Cmaj7 = C, E, G, B (root, 3, 5, 7):
Chord Tones Alone Create Melody
With just 3–4 notes per chord, you can already create melodic lines — because the harmonic center shifts naturally with each chord change.
The key is choosing notes that connect smoothly across chord changes:
- Dm7’s b7 (C) → G7’s 3rd (B): half step down
- G7’s b7 (F) → Cmaj7’s 3rd (E): half step down
- G7’s 3rd (B) → Cmaj7’s root (C): half step up
This smooth movement between chord tones is called voice leading. Listen to a phrase built from chord tones only:
Step 2: Scales = Filling the Gaps Between Chord Tones
Once you can play chord tones, add scale notes in between.
Here’s the key mental shift: don’t think of scales as “7-note patterns to memorize.” Think of them as passing tones that connect chord tones.
Scales for Each Chord
All three II-V-I chords are diatonic to C major, so their scales (modes) all use the same notes:
| Chord | Scale | Non-chord tones (passing) |
|---|---|---|
| Dm7 | D Dorian | E (9th), G (11th), B (13th) |
| G7 | G Mixolydian | A (9th), C (11th), E (13th) |
| Cmaj7 | C Major | D (9th), F (11th), A (13th) |
Here’s the insight: all three scales use the exact same 7 notes (C, D, E, F, G, A, B). Only the starting point differs.
This means if you play C major scale while targeting each chord’s tones, you’re automatically playing the right scale. “Switching scales” isn’t about changing notes — it’s about shifting which chord tones you emphasize.
Listen to the chord tone phrase with passing tones added:
View scale positions in the scale chart.
Step 3: Add Tensions to V7
With chord tones + scale notes under your fingers, here’s the final step. The chord with the most room for color is V7 (G7).
As a dominant chord, G7 can take altered tensions that increase the sense of resolution to Cmaj7.
Finding Tensions from Chord Tones
No new positions to memorize. Shift your fingers one fret from chord tones you already know:
| Tension | How to find it | Fretboard movement |
|---|---|---|
| b9 (Ab) | Half step above root | G → one fret up |
| #9 (Bb) | Half step below 3rd | B → one fret down |
| b5 (Db) | Whole step above 3rd | B → two frets up |
| #5 (Eb) | Half step above 5th | D → one fret up |
In the fretboard diagram below, chord tones (R, 3, b7) are highlighted. Everything else is an altered tension. Notice how they sit right next to the chord tones:
Where Tensions Resolve
Tensions create dissonance. That dissonance gains meaning when it resolves to a Cmaj7 chord tone.
| Tension (G7alt) | → Resolves to (Cmaj7) | Movement |
|---|---|---|
| b9 (Ab) | 5th (G) | Half step down |
| #9 (Bb) | Root (C) | Whole step up |
| b5 (Db) | 3rd (E) | Whole step up |
| #5 (Eb) | 3rd (E) | Half step up |
When you play a tension, aim for these landing points when Cmaj7 arrives:
Compare this with the scale phrase from Step 2. The Dm7 part is identical, but G7 now uses altered tensions (#5, #9, b9). Notice how the tension → resolution contrast is much stronger when landing on Cmaj7’s E4:
For more on the altered scale, see The Altered Scale Explained.
Summary
Improvising over II-V-I becomes simple when you think in three layers:
- Chord tones only — Find R, 3, 5, 7 for each chord on the fretboard. Connect them smoothly across changes.
- Scales fill the gaps — Add passing tones between chord tones. In II-V-I, all three scales share the same 7 notes (C major).
- Altered tensions on V7 — Shift one fret from chord tones to find altered tensions. Resolve them to the next chord’s tones.
Start with Step 1: play through II-V-I using chord tones only. Once they’re in your fingers, scales and tensions will follow naturally.
Check chord shapes in the chord chart and scale positions in the scale chart.
