Dean was born into slavery in Loudoun County on April 15, 1848, and was the daughter of Charles Dean and Annie Stewart Dean. Having secured her freedom as a consequence of the American Civil War (1861–1865), she attended schools in Fairfax County and in Washington, D.C. Dean worked as a domestic servant to help her family purchase a farm in Prince William County after her father’s death and to pay for one of her sisters’ schooling. She attended Sunday school at the First Congregational Church in Washington and later joined the Nineteenth Street Baptist Church there. She never married.
Dean began a lifetime of missionary work and dedication to racial uplift when she founded a Sunday school in Prince William County about 1878. She established additional Sunday schools in the area, several of which became congregations, including Calvary Chapel (later Greater Mount Calvary Christian Church). Dean raised money locally and in northern cities for construction of church buildings. Sh