Will Marion Cook ("né" William Mercer Cook) was born soon after the Civil War in 1869 in Washington, D.C. to John Hartwell Cook and his wife Isabel. The senior Cook had been in the first class of the Howard University School of Law, graduating in 1871 and becoming one of the first black lawyers to practice in Washington. He served as "chief clerk of the Freedmen's Bureau from 1867 until 1872 and as professor and dean of the Howard University Law School from 1876 until 1878." His parents were free people of color before the war, and stressed education; Cook had graduated from Oberlin College.