VII. Composing Musical Settings for Vernacular Texts
54. Translators of texts to be set to music should take care to combine proper conformity to the Latin and adaptability to the music. They are to respect the idiom and grammar of the vernacular and the proper characteristics of the people. Composers of new melodies are to pay careful heed to similar guidelines, as well as the laws of sacred music.
The competent territorial authority must accordingly see to it that experts in music and in Latin and the vernacular form part of the commission charged with preparing translations and that their cooperation enters into the work from the very outset.
55. The competent territorial authority will decide whether the vernacular texts traditionally associated with certain melodies may be used, even though these texts do not correspond exactly to the approved translations of liturgical texts.
56. Of special importance among the melodies to be composed for vernacular texts are those that belong to the priest and ministers for singing alone, together with the congregation, or in dialogue with the congregation. Composers of these melodies are to study whether the corresponding traditional melodies of the Latin liturgy may suggest melodies for use with the same texts in the vernacular.
57. New melodies for the priest and ministers must receive the approval of the competent territorial authority. 
58. The bodies of bishops concerned are to see to it that there is a single vernacular translation for a single language used in different regions. It is advisable also to have, as far as possible, one or more common melodies for the priest's and ministers' parts and for the congregation's acclamations and responses. This will foster a shared way for people of the same language to take part in the liturgy.
59. In their approach to a new work, composers should have as their motive the continuation of the tradition that provided the Church a genuine treasury of music for use in divine worship. They should thoroughly study the works of the past, their styles and characteristics; at the same time they should reflect on the new laws and requirements of the liturgy. The objective is that "any new form adopted should in some way grow organically from forms already existing"  and that new works will become a truly worthy part of the Church's musical heritage.
60. New melodies for the vernacular texts obviously require a period of testing in order to become firmly established. But their use in church purely for the sake of trying them out must be avoided, since that would be out of keeping with the holiness of the place, the dignity of the liturgy, and the devotion of the faithful.
61. The attempt to adapt sacred music in those areas that possess their own musical tradition, especially mission lands, requires special preparation on the part of musicians.  The issue is one of harmoniously blending a sense of the sacred with the spirit, traditions, and expressions proper to the genius of those peoples. All involved must possess a sufficient knowledge of the Church's liturgy and musical tradition as well as of the language, the popular singing, and the other cultural expressions of the people for whom they labor.