Volumes 1-6 describe Thompson's first missionary trip (1887-1899), detailing her preparations for travel to Africa, her arrival, and her first encounters with native Africans. During this time Thompson married another missionary, William L. Thompson, and together they traveled for four months, mostly on foot, from South Africa to Rhodesia (Zimbabwe). They settled at Mount Silinda, which would be their home in Africa for the next forty years.
The Mary McCornack Thompson Diaries were received by the Rare Book, Manuscript, and Special Collections Library as a gift in 2004. Originally, the papers of Mary McCornack Thompson were at Oberlin College, but were reacquired by the family at an unknown date.