The history of the Rosary is a complicated one, involving 2 different Dominics, Marian apparitions and popular devotions that developed over time.
It is commonly held that in 1208 St. Dominic de Guzmán received a heavenly vision of the Blessed Mother, who instructed him to spread a new devotion called the Rosary. Ever since then, St. Dominic and his Dominican religious order have been associated with the invention of the Rosary and its spread throughout Europe.
In truth, historical documents can neither confirm nor deny St. Dominic’s vision. The Dominican Friars Province of St. Joseph explains this history on its website.
It may indeed be true, but there is no documentation from the early 13th century to prove or disprove it. On the contrary, the meticulous depositions taken from eyewitnesses to investigate the life of Saint Dominic during his canonization process, although they mention many of his miracles and revelations, say nothing about the Rosary.
There is evidence of a vision St. Dominic received from Our Lady, but nothing explicit that connects it to the invention of the Rosary.
Interestingly, there is another St. Dominic who is often mentioned in connection with the development of the Rosary as we know it today.
This St. Dominic, according to the Catholic Encyclopedia, was a “Carthusian monk and ascetical writer, born in Poland, 1382.” There is substantial evidence that he added to existing devotions that involved the counting of prayers and created meditations on the life of Christ.
To the one hundred fifty Ave Marias which in those days formed the “Psalter of Mary” he had the thought of adding meditations on the life of Christ and of His Holy Mother. As in his time the Ave Maria terminated with the words; “Fructus ventris tui, Jesus,” he joined to each sentence to recall to mind the mystery … Both Dominic and his friend Adolf sought to spread the use of this form of prayer in the Carthusian Order and among the laity. For these reasons it is held by some authors that the “Psalter” of Dominic was the form, or one of the original forms, from which the present Rosary developed.
Prior to both St. Dominics, there existed various practices among the laity of counting 150 Our Fathers or Hail Marys to correspond to the 150 Psalms that priests and religious would recite in the Divine Office.
Regardless of which saint “invented” the Rosary as we know it today, what is true is that many Dominicans have spread this devotion since the 15th and 16th centuries and remain to this day the chief promoters of the devotion around the world. For example, it was a Dominican pope, St. Pius V, who promoted the Rosary and instituted the Feast of Our Lady of Victory in 1571 (later renamed the Feast of Our Lady of the Rosary in 1573 by Pope Gregory XIII).
The Rosary remains a staple of Roman Catholic piety and is a favorite of many Catholics around the world.