He is credited as the founding father of Iran's first modern Western medical school, Westminster College (now Urmia University) in 1879.

He was assigned by the Presbyterian Board of Foreign Missions as a missionary physician to Persia and returned to Urmia with his wife.

On Joseph's earnest request, and with funding from congregation members of the Westminster Church of Buffalo and the Presbyterian Board of Foreign Missions (operated by the Presbyterian Church in the United States of America; PCUSA) a 15-acre lot of land was purchased which became the site of Iran's first medical college, as well as missionary residences, and eventually a college.

[3] For this purpose, he erected a wooden building, which included a research laboratory, near the hospital, where the future medical personnel were to be trained.

[1] Joseph Cochran died of Typhoid fever in Urmia at the age of 50, on 18 August 1905,[6] on the second floor of his wooden house in the medical school.

[9] His son, Joseph Cochran, Jr, returning to Iran in 1920, followed in his father's footsteps through his services in the American Mission Hospital.

His daughter, Dorothy Cochran-Romson, served for a short time as a missionary nurse in Tabriz capital East Azerbaijan Province in Iran.