 Born on April 8, 1874 in Washington, D.C., Cromwell was the daughter of Lucy McGuinn and John Wesley Cromwell, and the eldest of six children.After graduating from the Miner Normal School (also known as the Normal School for Colored Girls), Cromwell taught in Washington, D.C. schools for several years before attending Howard University.In 1898 she transferred to Smith College, and graduated in 1900.