Monsignor, pl. monsignori, is the form of address for those members of the clergy of the Catholic Church holding certain ecclesiastical honorific titles. Monsignor is the apocopic form of the Italian monsignore, from the French mon seigneur, meaning "my lord". It is abbreviated Mgr, Msgr, or Mons.
As a form of address, "Monsignor" is not itself an appointment (properly speaking, one cannot be "made a monsignor" nor can one be "the monsignor of a parish"). The three honorary awards most often associated with the style "monsignor" are Protonotary Apostolic, Honorary Prelate, and Chaplain of His Holiness. These are granted by the Pope, usually at the request of the local bishop. The style is also associated with the office of vicar general.
Title and forms of address 
In some countries, Monsignor (or its foreign language equivalent) is the usual style of address for all higher prelates of the Roman Church below the rank of cardinal or patriarch, including bishops and archbishops. In other countries, particularly English-speaking ones, it is not used for bishops, but only for priests who have received certain specific honorary awards or who hold certain offices.
The written form of address for a priest-monsignor is Monsignor (first name) (last name) or The Reverend Monsignor (first name) (last name). The spoken form of address is Monsignor (last name).
Before the simplification of ecclesiastical titles in 1969, those of the lowest class were addressed in English as The Very Reverend Monsignor (in Latin, Reverendissimus Dominus; in Italian, Reverendissimo Monsignore) and those belonging to the higher classes were addressed as The Right Reverend Monsignor (in Latin, Illustrissimus et Reverendissimus Dominus; in Italian, Illustrissimo e Reverendissimo Monsignore)
The 1969 Instruction of the Secretariat of State indicated that the title of "Monsignor" may be used for Bishops. This is normal practice in Italian, French and Spanish. It is unusual in English. The same instruction indicated that, in the case of Bishops, "Reverendissimus" (usually translated in this case as "Most Reverend", rather than "Very Reverend"), may be added to the word "Monsignor", as also in the case of prelates without episcopal rank who head offices of the Roman Curia, judges of the Rota, the Promotor General of Justice and the Defender of the Bond of the Apostolic Signatura, the Apostolic Protonotaries "de numero", and the four Clerics of the Camera.
Classes of monsignori 
Pope Paul VI's motu proprio Pontificalis Domus of 28 March 1968 simplified the classification of monsignori or lesser prelates. Previously they were divided into at least 14 different grades, including domestic prelates, four kinds of protonotaries apostolic, four kinds of papal chamberlains, and at least five types of papal chaplains.
Since 1968, Apostolic Protonotaries are classified either de numero or supernumerary. Most of the former classes of Chamberlains and Chaplains have been abolished, leaving only a single class of "Chaplains of His Holiness", a specifically priestly-sounding category.
As a result monsignori are now classed into the following three ranks, in descending order of precedence:
- Apostolic Protonotary, of which two types are retained:
- de numero (the highest and least common form, customarily only seven)
- supernumerary (the highest grade of monsignor found outside Rome)
- Honorary Prelate of His Holiness (formerly "Domestic Prelate")
- Chaplain of His Holiness (formerly "Supernumerary Privy Chamberlain")
For the history of each of these classes of monsignori, see the article on each.
Before 1968, the appointment of a Privy Chamberlain expired at the death of the Pope who granted it. This no longer holds. Those listed in the index of the Annuario Pontificio as Chaplains of His Holiness continue to be listed in the edition that follow the death of the Pope, as after the deaths of Popes Paul VI and John Paul I in 1978 and after that of Pope John Paul II in 2005.
Ecclesiastical dress 
The 1969 Instruction of the Secretariat of State also simplified the dress of monsignori.
- Chaplains of His Holiness use a purple-trimmed black cassock with purple sash for all occasions.
- Honorary Prelates use a red-trimmed black cassock with purple sash for all occasions. The red is the same shade as that used by bishops. They may use a purple cassock as their choir dress for liturgical events of special solemnity.
- Supernumerary Apostolic Protonotaries dress the same as Honorary Prelates. As an additional privilege, they have the option of also using a purple ferraiuolo, a silk cape worn with the red-trimmed black cassock for non-liturgical events of special solemnity (for instance, graduations and commencements).
- Apostolic Protonotaries de numero (and other superior prelates of the offices of the Roman curia who are not bishops and who, as indicated above, may be addressed as Most Reverend Monsignor) have the same dress as other Apostolic Protonotaries, but wear the mantelletta in choir and a black biretta with a red tuft. They are thus called prelati di mantelletta (prelates of the mantelletta) because of this distinctive item of dress.
Other monsignori 
Under legislation of Pope Pius X, vicars general and vicars capitular (the latter are now called diocesan administrators) are titular (not actual) Protonotaries durante munere, i.e. as long as they hold those offices, and so are entitled to be addressed as Monsignor.
The only privileges of dress that Pope Pius X granted them were a black silk fringed sash, black piping on the biretta with a black tuft, and a black mantelletta. As a result of this they were in some countries referred to as "black protonotaries." However, "Pontificalis domus" of Paul VI removed this position from the Pontifical Household, even though the title of "monsignor", which is to be distinguished from a prelatial rank, has not been withdrawn from vicars general, as can be seen, for instance, from the placing of the abbreviated title "Mons." before the name of every member of the secular (diocesan) clergy listed as a vicar general in the Annuario Pontificio. (Honorary titles such as that of "Monsignor" are not considered appropriate for religious.)
The Secretariat of State has set minimum qualifications of age and priesthood for the appointment of Chaplains of His Holiness (35 years of age and 10 of priesthood), Honorary Prelates (45 of age and 15 of priesthood) and Protonotaries Apostolic Supernumerary (55 of age and 20 of priesthood). However, it waives the minimum age limit for vicars general proposed for appointment as Honorary Prelates, in view of the fact that, as long as they hold the office of vicar general, they also hold the still higher rank of Protonotary Apostolic Supernumerary. For the same reason, the Secretariat of State does not consider it appropriate that someone who is already a vicar general be appointed only a Chaplain of His Holiness.
See also 
- New York Times, Telegraph: The Rt Rev Mgr Graham Leonard, Australian Catholic Directory, Diocese of Paisley: Clergy within Diocese
- Especially in the United States e.g. Roman Catholic Diocese of Dallas, Diocese of Miami, Diocese of Tyler
- E.g. Diocese of Derry, Parish of Zejtun, Malta. This is the regular abbreviation in Italian.
- Instruction on the Dress, Titles and Coat-of-Arms of Cardinals, Bishops and Lesser Prelates (31 March 1969), English translation published by the Vatican: "26. For Supernumerary Apostolic Protonotaries, Prelates of Honour and Chaplains of His Holiness there may be used the title 'Monsignor', preceded, where appropriate, by 'Reverend'."
- 1969 Instruction, 23-25
- Galles, Chaplains of His Holiness
- Annuario Pontificio 2012, p. 1853
- Annuario Pontificio 2012, p. 1853
- "Pariter, qui vicarii generalis aut etiam capitularis munere fungitur, hoc munere dumtaxat perdurante, erit protonotarius titularis" (Pope Pius X, Inter multiplices curas, 62. 21 February 1905).
- "Super habitu quotidiano, occasione solemnis conventus, audientiae et similium... zonam tantum sericam nigram, cum laciniis item nigris, gestare poterunt, cum pileo chordula ac floccis nigris ornato" (Inter multiplices curas, 67).
- Noonan, The Church Visible.
- Baumgarten, Paul Maria (1913). "Monsignor". Catholic Encyclopedia. New York: Robert Appleton Company.
- Boudinhon, A. (1913). "Monseigneur". Catholic Encyclopedia. New York: Robert Appleton Company.
- Galles, Duane L.C.M (March 19, 1999). "Chaplains of His Holiness". St. Joseph Foundation. Retrieved 2006-09-01.
- Heim, Bruno Bernard (1978). Heraldry in the Catholic Church. Humanities Press. ISBN 0-391-00873-0.
- Instruction on the dress, titles and coat-of-arms of cardinals, bishops and lesser prelates.. L'Osservatore Romano, English ed. 17 April 1969. pp. vol.4. Retrieved 2006-09-01. Latin text of the Instruction, with an unofficial English translation
- Kirsch, J.P. (1913). "Prothonotary Apostolic". Catholic Encyclopedia. New York: Robert Appleton Company.
- Noonan, Jr., James-Charles (1996). The Church Visible: The Ceremonial Life and Protocol of the Roman Catholic Church. Viking. pp. 315–6. ISBN 0-670-86745-4.
- Pope Paul VI. (28 March 1968). Pontificalis domus. On the Papal Household, Reform of the Use of Pontifical Insignia, Simplification of Pontifical Rites and Insignia. Washington, DC: United States Catholic Conference, 1968. Latin Italian
- Pope Paul VI. (21 June 1968). Pontificalis insignia. Latin Italian