Jane Leasor was born August 22, 1922, in Portsmouth, Ohio. After her father's death, her mother married again, to Will Mac Donald of Wheaton, Illinois. She attended Wheaton Academy from 1936 to 1940 and Wheaton College from 1940 to 1944, from which she graduated with an A.B. degree in music. After Wheaton, she attended Biblical Seminary in New York City, where she received her master's degree in religious education in 1952. For the next two years, she taught at Belhaven College in Jackson, Mississippi. She was then accepted by the Presbyterian USA mission board and assigned to the position of teacher of Bible and music at the American College of Women in Beirut, Lebanon.

After a brief period of orientation, Leasor sailed for Lebanon in August of 1954. For a year she taught in a secondary school for girls attached to the College of Women and than taught at the College itself. During the summer of 1956, she attended a seminar for theological students at the Ecumenical Institute in Geneva, Switzerland. The next summer she spent on furlough in Wheaton. In 1959, she returned to the United States because of the serious illness of her mother. After working briefly at the consulate of the United Arab Republic in Chicago, she returned to Wheaton as secretary to Wheaton President V. Raymond Edman. From 1961 to 1964, she was Director of Community Services and Student Life at Biblical seminary in New York. She then went to Columbia University, where she was a student counselor. At the same time, she attended New York University, from which she received her Ph.D. in 1968. In 1980, she returned to Beirut to Beirut University College (formerly the American College for Women). However, after about two years, she had to return to the United States because of illness, and she settled in Wheaton.