Jus novum (c. 1140-1563) Jus novissimum (c. 1563-1918) Jus codicis (1918-present) Other Sacraments Sacramentals Sacred places Sacred times Supra-diocesan/eparchal structures Particular churches Juridic persons Philosophy, theology, and fundamental theory of Catholic canon law Clerics Office Juridic and physical persons Associations of the faithful Pars dynamica (trial procedure) Canonization Election of the Roman Pontiff Academic degrees Journals and Professional Societies Faculties of canon law Canonists Institute of consecrated life Society of apostolic life Tra le sollecitudini (Italian for "among the concerns") was a motu proprio issued 22 November 1903 by Pope Pius X that detailed regulations for the performance of music in the Catholic Church.

It begins: "Among the concerns of the pastoral office, ... a leading one is without question that of maintaining and promoting the decorum of the House of God in which the august mysteries of religion are celebrated...."[1] The regulations pointed toward more traditional music and critiqued the turn toward modern, orchestral productions at Mass.

It recognized that some modern compositions are "of such excellence, sobriety and gravity, that they are in no way unworthy of the liturgical functions", but warned that they needed to be "free from reminiscences of motifs adopted in the theaters, and be not fashioned even in their external forms after the manner of profane pieces".

Texts of the variable and common parts of the liturgy should always be in Latin and sung "without alteration or inversion of the words, without undue repetition, without breaking syllables, and always in a manner intelligible to the faithful who listen".

[7] The failure to allow for strings excluded many classical works composed expressly for liturgical use, including the many settings of the ordinary of the Mass by Haydn and Schubert, Mozart's Requiem, and Beethoven's Missa Solemnis.