“Deck the Halls” is a jazz-style piano arrangement of the traditional Welsh carol, arranged by Martha Mier. It is written in 4/4 time and marked “Slow, with swing.” The arrangement uses the familiar Christmas melody, but gives it a bluesy character through swung eighth notes, triplet figures, chromatic notes, slurs, dynamic changes, left-hand bass motion, and jazz-influenced harmonies.

Measures 1–4 introduce the swing style before the main melody begins. The right hand plays a decorated melodic line with triplet motion and slurs, while the left hand supports with low bass notes and simple harmonic movement. The opening moves from mezzo-piano to mezzo-forte, setting up the relaxed jazz sound.

Measures 5–12 present the first half of the carol. The right hand carries the melody for “Deck the halls with boughs of holly” and “‘Tis the season to be jolly,” while the left hand adds bass notes and chord tones underneath. The familiar “Fa la la” phrases are shaped with slurs and small rhythmic changes.

Measures 13–18 continue the carol with “Don we now our gay apparel” and “Troll the ancient Yuletide carol.” The melody stays clear in the right hand, while the left hand adds more chromatic color and low-register support. The dynamic grows to forte during the stronger “Fa la la” phrase.

Measures 19 to the end form the closing section. The music stretches through a long slur, returns briefly to mezzo-piano, then grows again before the final phrase. A ritardando leads into the last soft chord, ending the arrangement quietly after the stronger jazz buildup.

Interesting fact: “Deck the Halls” is connected to the Welsh tune “Nos Galan,” which means “New Year’s Eve.” This arrangement keeps the well-known Christmas melody but changes its character by using a slow swing style.