Public vs. Private Litanies

For those new to Catholicism - and even those of us who have been Catholic for a long time - we may be unfamiliar with what is a public versus a private litany. 

A good summary is given by the Catholic Encyclopedia of litanies and the distinction of public versus private:

A litany is a well-known and much appreciated form of responsive petition, used in public liturgical services, and in private devotions, for common necessities of the Church, or in calamities — to implore God's aid or to appease His just wrath. This form of prayer finds its model in Psalm cxxxv: 'Praise the Lord, for he is good: for his mercy endureth for ever. Praise ye the God of gods . . . the Lord of lords . . . Who alone doth great wonders . . . Who made the heavens', etc., with the concluding words in each verse, "for his mercy endureth for ever."...

...Litanies appeared in honour of God the Father, of God the Son, of God the Holy Ghost, of the Precious Blood, of the Blessed Virgin, of the Immaculate Conception, of each of the saints honoured in different countries, for the souls in Purgatory, etc.

In 1601 Baronius wrote that about eighty forms were in circulation. To prevent abuse, Pope Clement VIII, by decree of the Inquisition of 6 Sept., 1601, forbade the publication of any litany, except that of the saints as found in the liturgical books and that of Loreto. To-day the litanies approved for public recitation are: of All Saints, of Loreto, of the Holy Name, of the Sacred Heart, of St. Joseph [Ed. and, approved in 1960, of the Most Precious Blood of Our Lord Jesus Christ].

Many more litanies exist but only the following six may be publicly prayed in liturgical settings.  So if you are planning to lead a group at a chapel, church, oratory, etc in a litany, make sure it is one of the following:

1. Litany of All Saints
2. Litany of the Blessed Virgin Mary (i.e. Litany of Loreto)
3. Litany of the Holy Name of Jesus
4. Litany of the Sacred Heart of Jesus
5. Litany of St. Joseph
6. Litany of the Precious Blood of Jesus

Many, many other litanies exist, and all of them may be prayed privately (assuming of course they don't contain heresy). I've posted several litanies over the years that are private litanies.

Fish Eaters provides the following overview of the The Litany of the Saints, the oldest of the six:

The Litany of the Saints -- the oldest of the litanies, dating to A.D. 595 -- is prayed liturgically at the Easter Vigil, during ordinations, on Rogation days, and also during solemn exorcisms, etc.. Privately, it is prayed any time one wishes, as with the other litanies, but is especially prayed after sundown on All Saints' Day in preparation for All Souls' Day, and on All Souls' Day itself.

This litany first invokes God in all Three Persons, then follow, in this order: Mary; the blessed spirits; St. Joseph and the Patriarchs and Prophets; the Apostles and Evangelists; all the disciples of the Lord; the Holy Innocents and the glorious martyrs; the holy Bishops and Confessors (those who suffer for the faith); the holy priests and Levites; the virgins and widows; and all holy men and women.