Not only do We earnestly exhort all Christians to give themselves to the recital of the pious devotion of the Rosary publicly, or privately in their own house and family, and that unceasingly, but we also desire that the whole of the month of October in this year should be consecrated to the Holy Queen of the Rosary.
We decree and order that in the whole Catholic world, during this year, the devotion of the Rosary shall be solemnly celebrated by special and splendid services. From the first day of next October, therefore, until the second day of the November following, in every parish and, if the ecclesiastical authority deem it opportune and of use, in every chapel dedicated to the Blessed Virgin — let five decades of the Rosary be recited with the addition of the Litany of Loreto.
We desire that the people should frequent these pious exercises; and We will that either Mass shall be said at the altar, or that the Blessed Sacrament shall be exposed to the adoration of the faithful, Benediction being afterwards given with the Sacred Host to the pious congregation. We highly approve of the confraternities of the Holy Rosary of the Blessed Virgin going in procession, following ancient custom, through the town, as a public demonstration of their devotion.
And in those places where this is not possible, let it be replaced by more assiduous visits to the churches, and let the fervor of piety display itself by a still greater diligence in the exercise of the Christian virtues.
[…] May now the Christian nations, excited by Our exhortations, and inflamed by your appeals, seek the protection of Mary with an ardor growing greater day by day; let them cling more and more to the practice of the Rosary, to that devotion which our ancestors were in the habit of practicing, not only as an ever-ready remedy for their misfortunes, but as a whole badge of Christian piety. The heavenly Patroness of the human race will receive with joy these prayers and supplications, and will easily obtain that the good shall grow in virtue, and that the erring should return to salvation and repent; and that God who is the avenger of crime, moved to mercy and pity may deliver Christendom and civil society from all dangers, and restore to them peace so much desired.
Pope Leo XIII, SUPREMI APOSTOLATUS OFFICIO