Arranging is deciding who plays what. A song on one guitar and the same song for a band can share every chord and still sound like two different records.
Arranging and orchestration
An arrangement adapts a composition: it may reharmonise it, paraphrase the melody, reorchestrate it or change its form. Orchestration is narrower: assigning notes to the instruments of an ensemble. In jazz, an arrangement the band has memorised rather than written down is a head arrangement.
Jobs, not parts
In a small band each instrument needs a job that nobody else is doing. The rhythm section of jazz and pop shows the pattern: one or more chord instruments (piano, guitar), a bass, and drums, under a soloist or a singer.
| Instrument | Job | Leave room by |
|---|---|---|
| Drums | Time and energy | Saving fills for the ends of sections |
| Bass | The root and the groove | Locking to the kick drum |
| Guitar or keys | The chords | Choosing one of them per section, or splitting the range |
| Voice or lead | The melody | Keeping the others out of its register while it sings |
Build by section
Use the arrangement to show the song form from lesson 3: fewer parts in the verse, more in the chorus, something new in the bridge. The breakout chorus is an arranging decision as much as a writing one.
Sources
Every date, name, tempo and origin on this page comes from these pages, read on 2026-10-24.