In Dorico Pro, an instrument is an individual musical instrument, such as a piano, a flute, or a violin. Human voices, such as soprano or tenor, are also considered instruments.

In Dorico Pro, instruments are held by players, just as real instruments are held by human players. Section players can only hold a single instrument but solo players can hold multiple instruments, which allows you to handle instrument changes easily, such as when an oboist doubling the cor anglais switches from one instrument to the other.

This means that before you can add instruments to a project, you must first add players or ensembles, which may in turn also be assigned to groups if needed. If you add ensembles, the appropriate instruments for the ensemble are automatically added to the players.

Each instrument automatically gets its own staff, but when instrument changes are allowed, the music for multiple instruments held by the same solo player can appear on the same staff as long as no notes overlap. By default, Dorico Pro allows instrument changes in all layouts and automatically shows instrument change labels. This means that only the top instrument held by players is shown automatically in the music area. You can see staves for all instruments in galley view, and you can allow/disallow instrument changes in each layout independently. You can also hide/show empty staves in each layout independently.

Instruments in Dorico Pro do not have limited ranges; it is possible to notate any pitch in any register on every instrument. However, in the piano roll editor in Play mode, only pitches that fall in the MIDI note range 0-127 can be represented. Similarly, if you input a pitch beyond the range of samples in the assigned VST instrument, the pitch does not sound in playback.

You can change instruments at any time, add/delete them from players, and move them between players.