DescriptionThis is a historical study of W. E. B. Du Bois’s quest to challenge scientific racism by educating Black Americans on Negro history and culture at the 135th Street Branch of the New York Public Library. W. E. B. Du Bois discovered that the silence and neglect of science had distorted and erased the truth regarding the history and culture of the Black race. Thus, he believed that it was his duty to change the perception of the Black race contrary to how science had defined it. Du Bois used the 135th Street Branch Library in its role in the Harlem community as an urban repository and a center for Black studies to educate the Black masses on Negro history and culture. To show that Blacks were not of an inferior race, Du Bois provided evidence to counter the claims of science. Du Bois developed an empirical framework based on social scientific research of Blacks in cities and engaged the scientific community on both the domestic and international fronts. This study examined the historical relationship between the evolution of Du Bois’s thinking on race and science and his “anti-racialism,” exemplified in two critical moments in his career: his attendance at the First Universal Race Congress in London and his work at the 135th Street Branch Library. The aim of this research was (a) to explain the history of scientific racism as it relates to the intellectual development of Du Bois’s thinking on race and science; (b) to understand Du Bois’s role in Harlem and how the 135th Street Branch library was a part of it, and (c) to describe the issues in the history of urbanization, cities, and race and how they relate to Du Bois and to Harlem. Historical research was applied in the form of (a) archives; (b) primary and secondary sources, such as articles, newspaper clippings, and monographs; (c) audiovisual materials, such as photos; and (d) observations. Validity and reliability of the findings derive from these multiple data sources. This work contributes to research in the fields of history, education, ethnology, anthropology, sociology, and urban studies.