In November 1876, Mary of the Passion went to Rome to regularize the situation of the twenty separated sisters and, on 6th January 1877, obtained the authorization from Pius IX to found a new Institute which was to be specifically missionary and was to be called the Missionaries of Mary.
On the suggestion of the Congregation of Propaganda Fide, Mary of the Passion opened a novitiate in Saint-Brieuc in France, where very soon numerous vocations came along. In April 1880, and in June 1882, the Servant of God went to Rome to resolve the difficulties which were threatening to hinder the stability and growth of the young Institute. This latter journey, on June 1882, marked an important stage in her life: in fact she was authorized to open a house in Rome and, through providential circumstances, she rediscovered the Franciscan direction which God had indicated to her twenty-two years previously. On 4th October 1882, in the Church of the Aracoeli, she was received into the Third Order of Saint Francis and thus began her relationship with the Servant of God, Fr. Bernardin de Portogruaro, Minister General, who with paternal solicitude would support her in her trials.
In March 1883, due to latent opposition, Mary of the Passion was deposed from her office of Superior of the Institute. However, after an inquiry ordered by Leo XIII, her innocence was fully acknowledged and at the Chapter of July 1884 she was re-elected.
The Institute of the Missionaries of Mary then began to develop rapidly. On 12th August 1885 the Laudatory Decree, and that of affiliation to the Order of Friars Minor were issued. The Constitutions were approved ad experimentum on 17th July 1890 and definitively on 11th May 1896. Missionaries were sent regularly to the most perilous and distant places overcoming all obstacles and boundaries.
The zeal of the Foundress knew no bounds in responding to the calls of the poor and the abandoned. She was particularly interested in the promotion of women and the social question: with intelligence and discretion she offered collaboration to the pioneers who were working in these spheres, which they appreciated very much.
Her intense activity drew its dynamism from contemplation of the great mysteries of faith. For Mary of the Passion, all led back to the Unity-Trinity of God Truth-Love, who communicates Himself to us through the paschal mystery of Christ. It was in union with these mysteries that, in an ecclesial and missionary dimension, she lived her vocation of offering. Jesus in the Eucharist was for her, "the great missionary" and Mary, in the disponibility of her "Ecce", traced out for her the path of unconditional donation to the work of God. Thus she opened her Institute to the horizons of universal mission, accomplished in Francis of Assisi's evangelical spirit of simplicity, poverty and charity .
She took great care, not only of the external organization of the works, but above all of the spiritual formation of the religious. Gifted with an extraordinary capacity for work, she found time to compose numerous writings on formation, whilst by frequent correspondence she followed her missionaries dispersed throughout the world, relentlessly calling them to a life of holiness. In 1900 her Institute received the seal of blood through the martyrdom of seven Franciscan Missionaries of Mary, who were beatified in 1946 and canonised during the Great Jubilee of the year 2000. To be the spiritual mother of these missionaries who had known how to live to the shedding of their blood, the ideal proposed by her, was for Mary of the Passion, both a great sorrow, a great joy and a time of great emotion.
Worn out by the fatigue of incessant journeys and daily labour, Mary of the Passion, after a brief illness, died peacefully in San Remo on 15th November 1904, leaving more than 2,000 religious and eighty-six houses scattered about the four continents. Her mortal remains repose in a private oratory of the General House of the Institute of the Franciscan Missionaries of Mary in Rome.
In February 1918, in San Remo, the Informative Process was opened for the Cause of Beatification and Canonization. In 1941, the Decree on the writings was promulgated and, during the following years, numerous postulatory letters were addressed to the Holy See from all parts of the world in favour of the Cause of the Servant of God. After the Consultors had voted unanimously in its favour, the Decree for the Introduction of the Cause was published on 19th January 1979, with the approbation of His Holiness John Paul II. On 28th June 1999 the Sovereign Pontiff John Paul II solemnly promulgated the Decree on the heroicity of the virtues of Mother Mary of the Passion
On 5th March 2002, the healing of a religious, suffering from "pulmonary and vertebral TBC, Pott's Disease", was recognized as a miracle granted by God through the intercession of the Venerable Mary of the Passion. On 23rd April 2002, in the presence of the Sovereign Pontiff John Paul II, the Decree opening the path for the Beatification of the Venerable Servant of God was promulgated.