This trombone music for Up On the Housetop is in the key of B flat. Select the image below for a printable PDF of the melody. The Up On the Housetop band play-along page has more versions of this song, so you can play it with other woodwind and brass instruments. The string arrangement of the carol is in the key of D. Visit the Up On the Housetop lead sheet page which features the carol in seven different keys. There you can find your desired instrumental range, or print an arrangement that allows you to play along with string instruments.
See the transposition page for explanations and charts to help you determine the appropriate key to play in when performing with instruments that are not in concert key. More Christmas songs for trombone.