Lucy was born in Berryville, Virginia to Henry Slowe and Fannie Porter Slowe. Her father was a hotel operator. However, her parents died while Lucy was at a young age. Orphaned, Lucy was raised by her aunt Martha Price in Lexington, Virginia. At thirteen, Lucy and her family moved to Baltimore, Maryland, where she attended Baltimore Colored School. She graduated second in the class in 1904 and was the first person from the school to attend Howard University.