Over the course of 25 years, Pennsylvania Railroad Company executive and land developer, Henry H. Houston, amassed a real estate portfolio spanning 3,000-plus acres in northwestern Philadelphia. Houston’s holdings in Germantown, an emerging Philadelphia suburb during the mid-Nineteenth century, have been overshadowed in terms of scholarly research by Houston’s large-scale community development in neighboring Chestnut Hill, Philadelphia. Accordingly, this thesis aims to uncover a comprehensive development narrative for Houston’s Germantown development, connecting land holdings, associated dwellings, architectural character, and social history together in order to determine if Houston’s role in Germantown was simply a precursor to later development or integral to suburbanization in Northwest Philadelphia. Key aspects of the historic narrative include: Germantown’s initial period of rapid suburbanization during the 1850s and subsequent suburban growth during the 1880s; Houston’s influence upon the character of the neighborhood both architecturally and demographically; and the overall significance of Houston-era development in Germantown as it relates to suburban development typologies established by scholars and preservation entities such as the National Park Service. Methodologically, this thesis utilizes archival research, field/site documentation through photography and GIS mapping, and secondary research spanning several contexts including suburban history, architectural history, and social history.