This thesis aims to depict American women’s “indispensable” participation in the United States’ foreign mission movement. The emphasis in this thesis is on missionary wives and single missionary women both in mission fields and in the missionary societies controlled in the United States. The concept of separate spheres of male and female influence forms the center point of this thesis and the participation of women in the foreign mission movement is discussed from this perspective. It was the divine sanction, the religious service that stimulated American women to enter the mission work in the 19th century. Although the starting point did not embrace a feminist frame, the process of implementation did lead American women into public roles independent of male influence. In the name of this accomplishment, this thesis aims to explore what many historians have neglected to analyze. American missionary women, in the United States or in the foreign mission lands, created a new professional career for educated women, broke the bondage of the domestic sphere, expanded the involvement of women in cultural and political interaction, and represented the American woman to the whole world.