Abstract: An apparatus for the translation of musical chords from one key to another key. Both the electronics and mechanical embodiments of the invention permit the user to translate a musical score in a source key to a target key by identifying the appropriate chords for the target key. In the mechanical embodiments, the source key is physically aligned with the target key. This positions the chords to also be in aligned or associated with each other. In the electronics embodiment, the user establishes the source key and the target key to establish the chord mapping. In one electronic embodiment, the operator also identifies the source chord for the absolute identification of the targeted chord. Optionally, a listing of the chord mapping is printed for later reference or for transcription onto the musical score.