Philadelphia’s public educational landscape has suffered from various forms of racial segregation over the past two centuries. While Pennsylvania prohibited racial discrimination against students in 1881, Philadelphia restricted Black educators to teaching only Black students in separate schools until 1937. This thesis investigates Philadelphia’s separate Black public school buildings from 1881 to 1937 in order to illustrate the role of architecture in school segregation, as well as to place the history of segregated education in the built environment. With attention to the scholarship of school buildings’ design history, this study requires a further analysis of architectural history which includes maintenance, adaptation, evolution, and use over time. Two components form the content of this work: an inventory of 25 school buildings and sites designated for separate Black public education; and a case study of the Martha Washington School in the Mill Creek neighborhood of northern West Philadelphia. The inventory shows that schools belonged to one or more of four architectural categories: ‘Secondhand,’ ‘New build,’ ‘Annex,’ and ‘Rebuild.’ The case study analyzes the transition of Martha Washington School (built 1874) from all-White, to mixed, to internally-segregated, to its designation as a separate all-Black facility. The half-century-old ‘Secondhand’ schoolhouse was demolished and replaced in 1929 with a ‘Rebuild’ school plant – modern, up-to-date, and purpose-built for continued separate Black education. Examining themes of Black educational heritage and Jim Crow architecture in Philadelphia, this thesis discusses legibility of school building sites as historic resources whose preservation and interpretation should encompass change over time.