Quanta Cura
- Condemning Current Errors. The fatal opinions include the political-religious philosophy of naturalism, promotion of an extreme form of religious liberty, and atheistic communism and socialism. Encyclical promulgated 8 December, 1864.
- http://www.papalencyclicals.net/Pius09/p9quanta.htm

Amantissimi Redemptoris
- On Priests and the Care of Souls. Encyclical promulgated 3 May, 1858.
- http://www.papalencyclicals.net/Pius09/p9amant1.htm

Syllabus of Errors
- Condemns various philosophies, religious attitudes, and opinions on the relation between Church and State. Issued in 1864.
- http://www.papalencyclicals.net/Pius09/p9syll.htm

Vix dum a nobis
- On the Church in Austria. Expresses opposition to proposed legislation which asserts that the civil government has authority over the Church. Encyclical promulgated 7 March, 1874.
- http://www.ewtn.com/library/ENCYC/P9VIXDUM.HTM

Ubi primum
- On the Immaculate Conception. Asks the bishops to pray about whether the Immaculate Conception should be defined as dogma. Encyclical promulgated 2 February, 1849.
- http://www.ewtn.com/library/ENCYC/P9UBIPR2.HTM

Ubi nos
- On the Pontifical States. Encyclical promulgated 15 May, 1871.
- http://www.ewtn.com/library/ENCYC/P9UBINOS.HTM

Singulari quidem
- On the Church in Austria. Encyclical promulgated 17 March, 1856.
- http://www.ewtn.com/library/ENCYC/P9SINGUL.HTM

Saepe venerabiles fratres
- Thanksgiving for 25 Years of Pontificate. Encyclical promulgated 5 August, 1871.
- http://www.ewtn.com/library/ENCYC/P9SAEPEV.HTM

Respicientes
- Protesting the Taking of the Pontifical States. Encyclical promulgated 1 November, 1870.
- http://www.ewtn.com/library/ENCYC/P9RESPIC.HTM

Quod nunquam
- On the Church in Prussia. Condemns recent anti-Catholic laws. Encyclical promulgated 5 February, 1875.
- http://www.ewtn.com/library/ENCYC/P9QUODNU.HTM

Qui pluribus
- On Faith and Religion. Pius IX's first encyclical, promulgated 9 November, 1846.
- http://www.ewtn.com/library/ENCYC/P9QUIPLU.HTM

Qui nuper
- On Pontifical States. Notifies bishops of rebellion in the Papal States, asks for prayers. Encyclical promulgated 18 June, 1859.
- http://www.ewtn.com/library/ENCYC/P9QUINUP.HTM

Quartus supra
- On the Church in Armenia. Quite a long letter on the nature of schism, and warning against new schismatics attempting to deceive Armenian Catholics. Encyclical promulgated 6 January, 1873.
- http://www.ewtn.com/library/ENCYC/P9QUARTU.HTM

Quanto conficiamur moerore
- On Promotion of False Doctrines. Encyclical promulgated 10 August, 1863.
- http://www.ewtn.com/library/ENCYC/P9QUANTO.HTM

Quae in patriarchatu
- On the Church in Chaldea. Encyclical promulgated 16 November, 1872.
- http://www.ewtn.com/library/ENCYC/P9QUAEIN.HTM

Probe noscitis venerabiles
- On the Discipline for Clergy. To the Spanish bishops, about proper formation of clergy. Encyclical promulgated 17 May, 1852.
- http://www.ewtn.com/library/ENCYC/P9PROBEN.HTM

Praedecessores nostros
- On Aid for Ireland. Calls on the bishops of the world to proclaim three days of public prayer for Ireland, and also to collect donations to financially support the Irish, who were then suffering from a worsening famine and widespread disease. Encyclical p
- http://www.ewtn.com/library/ENCYC/P9PRAEDE.HTM

On Episcopal Meetings
- To the bishops of the Austrian Empire. Praises the faith of Emperor Franz Josef, urges the bishops to hold councils and provincial and diocesan synods. Encyclical promulgated 5 November, 1855.
- http://www.ewtn.com/library/ENCYC/P9OPTIM2.HTM

Optime noscitis
- On the Proposed Catholic University of Ireland. Tells the bishops to go forward with their plan, and approves their choice of John Henry Newman as rector. Encyclical promulgated 20 March, 1854.
- http://www.ewtn.com/library/ENCYC/P9OPTIM1.HTM

Omnem sollicitudinem
- On the Greek-Ruthenian Rite. Forbids any changes be made to Eastern Catholic liturgies, and in particular to the Ruthenian Rite. Encyclical promulgated 13 May, 1874.
- http://www.ewtn.com/library/ENCYC/P9OMNEMS.HTM

Nullis certe verbis
- On the Need for Civil Sovereignty. Rejects Napoleon III's advice that Pius IX surrender the Papal States. Encyclical promulgated 19 January, 1860.
- http://www.ewtn.com/library/ENCYC/P9NULLIS.HTM

Ineffabilis Deus
- Defines the Immaculate Conception infallibly as dogma. Apostolic Constitution issued by Pope Pius IX on 8 December, 1854.
- http://www.catholic-forum.com/saints/bvm00013.htm

Nostis et nobiscum
- On the Church in the Pontifical States. Encyclical promulgated 8 December, 1849.
- http://www.ewtn.com/library/ENCYC/P9NOSTIS.HTM

Nemo certe ignorat
- On Discipline for Clergy. Urges unity of the bishops of the British Isles, encourages the foundation of the Catholic University of Ireland. Encyclical promulgated 25 March, 1852.
- http://www.ewtn.com/library/ENCYC/P9NEMOCE.HTM

Neminem vestrum
- On the Persecution of Armenians. Clarifies the current status of the Mechitharist monks, deplores dissension and schisms among Armenian Catholics. Encyclical promulgated 2 February, 1854.
- http://www.ewtn.com/library/ENCYC/P9NEMINI.HTM

Meridionali Americae
- On the Seminary for Native Clergy. To the bishops of South America. Expresses joy at the increase in indigenous clergy and concern for their proper formation. Encyclical promulgated 30 September, 1865.
- http://www.ewtn.com/library/ENCYC/P9MERIDI.HTM

Maximae quidem
- On the Church in Bavaria. Encyclical promulgated 18 August, 1864.
- http://www.ewtn.com/library/ENCYC/P9MAXIMA.HTM

Levate
- On the Afflictions of the Church. Decries attacks on the Church in Russia, Poland, and Italy. Encyclical promulgated 21 October, 1867.
- http://www.ewtn.com/library/ENCYC/P9LEVATE.HTM

Incredibili
- On persecution in New Granada. Encyclical promulgated 17 September, 1863.
- http://www.ewtn.com/library/ENCYC/P9INCRED.HTM

Gravibus Ecclesiae
- Proclaims a Jubilee Year for 1875. Encyclical promulgated 24 December, 1874.
- http://www.ewtn.com/library/ENCYC/P9GRAVIB.HTM

Graves ac diuturnae
- On the Church in Switzerland. Condemns the Old Catholics and anti-Catholic marriage laws. Encyclical promulgated 23 March, 1875.
- http://www.ewtn.com/library/ENCYC/P9GRAVES.HTM

Exultavit cor nostrum
- On the Effects of the Jubilee. Encyclical promulgated 21 November, 1851.
- http://www.ewtn.com/library/ENCYC/P9EXULTA.HTM

Etsi multa
- Denounces actions against the Church by the governments of Italy, Germany, and Switzerland. Encyclical promulgated 21 November, 1873.
- http://www.ewtn.com/library/ENCYC/P9ETSIMU.HTM

Cum Sancta Mater Ecclesia
- Pleading for Public Prayer. Urges bishops and the faithful to beg God "banish war to the very ends of the earth." Encyclical promulgated 27 April, 1859.
- http://www.ewtn.com/library/ENCYC/P9CUMSAN.HTM

Cum nuper
- Care for Clerics. Written to the Sicilian bishops. Urges a high standard of morality for clergy and laity alike. Encyclical promulgated 20 January, 1858.
- http://www.ewtn.com/library/ENCYC/P9CUMNUP.HTM

Beneficia Dei
- Encyclical promulgated 4 June, 1871, commemorating the 25th anniversary of his pontificate.
- http://www.ewtn.com/library/ENCYC/P9BENEFI.HTM

Apostolicae Nostrae Caritatis
- Urging Prayers for Peace. Encyclical promulgated 1 August 1854.
- http://www.ewtn.com/library/ENCYC/P9APOSTO.HTM

Amantissimus
- On the Care of Churches. Establishes a Congregation for Eastern Rites. Encyclical promulgated 8 April, 1862.
- http://www.ewtn.com/library/ENCYC/P9AMANT2.HTM