This is a 3-part arrangement, with 2 optional extra harmonies. It’s a very well-known tune but, typically for jazz songs of this era, it’s not completely straightforward, due to some interesting melodic leaps and tricky key changes. The harmonies are not in themselves particularly complex, but they all have to negotiate the key changes between sections, so I would describe both the 3-part and 5-part versions as moderate, but with Some Challenges. If you want a relatively easy taster for your group, stick with the verses.
This song was written in 1934, but in 1953, new children’s lyrics were added to the second middle section, and these helped to make the song even more popular. Nowadays, there’s barely a shop or café that doesn’t play this song for months in the lead up to Christmas! I wanted to create an arrangement that keeps both the romantic feel of the verses and the jolliness of the middle sections. I nearly always stick with the 3-part version in my workshops, as I prefer not to spend too long on Christmassy songs. However, performance groups may appreciate the extra rhythms and texture added by Voices 4 and 5, and regular groups may enjoy adding more harmonies after a few years of having the song in their festive repertoire, just to keep the interest going!