Once In a While is scored as an easy to play vocal feature in the key of Ab, making it singable by most Alto or Baritone voices. After a short intro the vocalist takes the first chorus, backed by reeds and muted brass. The brass opens up and takes the lead in the instrumental bridge, then the vocalist leads into the middle eight, backed by the Trombones. The final half chorus sees a restatement of the opening feel and the chart concludes with a neat little unison brass run down to a final sax sustain. There are no sax doubles.