Donald Arthur Cook was born May 15, 1923, in Earlham, Iowa, and grew up in a family which included two brothers and one sister. During his childhood, the family left Iowa when their farm failed and moved to Downers Grove, Illinois, where his father took a job in the post office. In his teens, Donald became a member of the Lisle Bible Church and was actively involved in church youth groups, where he met his future wife, Dorothy True. After attending Downers Grove Community High School and graduating in 1941, he enrolled in Wheaton College.

World War II interrupted his education at Wheaton, and Donald spent the years between 1943 and 1946 in the Pacific as an Air Force navigator. He returned to the Wheaton campus in 1947 and graduated in January 1950, with a major in sociology after changing from an earlier concentration in business administration. In his junior year, he made the decision to make full-time ministry his vocation and he enrolled next at Faith Theological Seminary, Wilmington, Delaware. He and Dorothy were married that year, 1950, and by the time of graduation in 1953, they were preparing to leave for the mission field.

His experience in the Pacific during the Air Force years resulted in an urgent interest in the Orient, China in particular. Exposure to the work of China Inland Mission (renamed Overseas Missionary Fellowship after the war) at Wheaton led Donald to decide to apply to CIM. The Cooks were sent first to Singapore for language study and orientation and, because work in China was no longer possible, they then chose to train for mission work in Japan. They arrived in Japan from Singapore in January 1957. One of their first assignments was to relieve missionaries leaving on furlough who had been working in a small town, Tomikawa, on the coast of Hokkaido.

In 1959 the Cooks moved to the headquarters in Tokyo, where there was a need of a staff member trained in business administration to assist with the distribution of mission supplies during the post-war disorganization in Japan. Their son, William, was born the next year, 1960, and a daughter joined the family in 1963. Between 1959 and 1969, Dorothy was in charge of the mission home in Tokyo while Donald remained in administrative work for OMF, utilizing his college training in that area.

They moved next to Sapporo, 1969-1971, where his wife was in charge of the mission home and later worked as secretary. Donald continued to work in the business administration of OMF. Between 1971 and 1972, both Cooks served as house parents for the Chefoo School in addition to their other duties. During a furlough the next year, concern for their children and the public nature of institutional living led to the decision not to return to the mission field. Donald re-entered the business world and in 1983 was employed by an insurance company in Wheaton where the Cooks lived. Donald retired in 2002 and died July 7, 2014 in Willmar, Minnesota