Young Father Cataldo's next assignment was to teach philosophy to the Jesuit novices at Santa Clara College. His health improved, but he still showed signs of tuberculosis, an excuse his Superior used to detain him longer than necessary. The house 'doctor' at Santa Clara, Brother Boggio, advised that a rigorous life in the missions would probably suit Cataldo better in the long run than a relatively easy one in California, so General Beckx ordered Cataldo free to fulfil his original assignment to the Jesuits' Rocky Mountain Mission.
Father Cataldo sailed from San Francisco in September, 1865, and thence up the Columbia River to Fort Walla Walla, Washington Territory. Accompanied by Father Joseph Giorda, his new Superior, Father Cataldo then traveled the Mullan Trail by horse to Sacred Heart Mission, Idaho Territory. Now twenty eight and alive with purpose, he could finally begin his dream of a missionary life--one he would be still living more than six decades later.