These twenty-one duets are arranged so that players on any two instruments can perform together. Not only may two like instruments such as two flutes play together, but two dissimilar instruments such as violin and tuba may perform all of the duets. Also, any number of band and orchestra instruments may play together in two part harmony from these books. Thus, directors can rehearse the music with large ensembles and assign pairs of players or groups of players to practice and perform together. It is suggested that when a high sounding and a low sounding instrument (violin and tuba for example) play a duet, the high instrument should generally play the top line while the low instrument plays the bottom line. Interesting effects can be obtained by combining several pairs of instruments. Two violins may play duets simultaneously with two cellos. Two flutes, two clarinets and two bassoons make an interesting triple duet group. Also, several like instruments (horns for example) can play the top part in unison while several other like instruments (tubas for example) play the bottom part.