The papers relate to missionary work in China and Thailand from 1888-1927, to educational institutions with which the Fosters were involved, and to the personal and family life of several generations of Foster family members. Correspondence mainly consists of letters received by various members of the Foster family. Of particular interest are the journals of John Marshall Foster, 1888-1916, describing life and events in China, especially the effects of the Boxer Rebellion on the American missions. The Fosters were a family of American Baptist missionaries. John Barton Foster, was a teacher, editor of Zion's Advocate, minister and professor of Greek and Latin at Colby College. His son, John Marshall Foster, helped found the Baptist Church at Vassalboro, Maine, and was a missionary to China and Thailand from 1888 to 1921. Clara Hess Foster, the wife of J. M. Foster, and their children Frank, Anna, and John Hess also served as missionaries in China. John Hess Foster was on the medical staff of Yale-in-China.