Born: November 22, 1863, Overhalla, Nord-Trøndelag fylke, Norway.
Died: September 20, 1938, Manitowoc, Wisconsin.
Buried: Evergreen Cemetery, Manitowoc, Wisconsin.
Ditlaf was the son of George and Johanna Bergitte Ristad, and husband of Sarah M. Johnson.
He taught at the Namsos Middle School in Norway. After serving three years in the army, he emigrated to America in 1887.
He attended Luther Seminary, St. Paul, Minnesota, and Chicago University.
He then served pastorates in Edgerton, East Koshkonong, Rockdale, and Manitowoc, Wisconsin.
From 1901–19, he served in turn as president of Albion Academy, Park Region Luther College, and the Lutheran Ladies Seminary, Red Wing, Minnesota.
In 1897 he edited the Lutheran Sunday-School Hymnal and served on the committee for the Lutheran Hymnary and the Lutheran Hymnary Junior.
He issued a book of Norwegian poetry in 1922.