This thesis assesses the extent to which historic decision-making tendencies influence contemporary Philadelphia policy. Philadelphia has a distinctive stock of rowhouses built throughout the nineteenth and twentieth centuries which today provides more housing units than are needed by the population. The excess housing stock means that Philadelphia could invest in reuse rather than new construction to meet demand for affordable rental housing, a path which avoids demolition and displacement in communities which have faced disinvestment in the past. However, current Philadelphia policy appears to favor new construction of housing. Using primary and secondary sources, this thesis examines patterns in past housing policy to identify recurring assumptions among policy-makers. It then uses interviews with housing professionals to identify case-study policies that influence real estate development: The Ten Year Tax Abatement, zoning, and support for property maintenance. Finally, it analyzes contemporary decision-maker statements to see whether the recurring assumptions shape their thinking about these policies. The analysis shows that assumptions do help explain why some of these policies are in their current form and why changing policy to support housing reuse has not occurred. However, the analysis also confirms that concrete factors like lack of funding also play a role in constraining change. This thesis is not an exhaustive overview of Philadelphia housing history or contemporary policy, and more research is needed to analyze how history impacts other Philadelphia policy areas or other cities.