It is scored for SATB choir and soloists, violin I, violin II, 2 trumpets, 3 trombones colla parte, 2 timpani, and basso continuo (violoncello, double bass, and organ, with optional bassoon obbligato).

[1] The title "de confessore" was not Mozart's own, and was added by a later hand to his manuscript.

It suggests that the work was intended for vespers held on a specific day on the liturgical calendar of saints ("confessors"); however, the saint in question has not been conclusively established if there even was one.

[3] Structurally, it is very similar to Vesperae solennes de Dominica (K. 321), composed in 1779.

The first three psalms are scored in a bold, exuberant manner, contrasting with the strict, stile antico counterpoint of the a cappella fourth psalm,[3] and the tranquility of the fifth movement.