Toward the end of the 1800s the phenomenon of migration reached dimensions never seen before. It is estimated that from 1815 to 1914 approximately 82,000,000 people left their countries to seek a future elsewhere. Among these, 55 million emigrated from Europe to America. How did Fr. Dehon perceive this phenomenon? Did he understand the motives of the emigrants; was he aware of the challenges that these people faced in a new land? Did he see in this movement a challenge — and an opportunity — for the Catholic mission and especially the apostolic project of the young congregation he founded? To these and other questions the contribution of Fr. Juan José Arnaiz Ecker — “Migration and Fr. Dehon ” — offers some answers. The article is available in Italian and Spanish.