In this chapter, we examine the Retrofit Philly Coolest Block Contest (Coolest Block contest) – a competition run in 2010 which gave residents of Philadelphia the opportunity to win a cool roof, air sealing and insulation upgrades by joining together and submitting an entry for their block. The contest was sponsored by the Energy Coordinating Agency of Philadelphia (ECA), Dow Chemical Company’s Building and Construction Division (Dow) and the City of Philadelphia Mayor’s Office of Sustainability (MOS). We explore the Coolest Block contest and its implications for addressing urban sustainability, infrastructure renewal and climate change in the City of Philadelphia. A port city on the Delaware River at the centre of a metropolitan region of approximately 6.3 million people, Philadelphia has always been a centre of commerce. From the late eighteenth century it was one of the most important ports on the East Coast of the American colonies, and it developed into a key industrial powerhouse in the early twentieth century with the development of rail links into the city. Rapid urban development followed industrialization in the form of rows of terraces constructed to provide housing for the burgeoning industrial workforce. However, Philadelphia’s fortunes turned with de-industrialization and decentralization after the 1950s. Factories closed, population declined and land lay vacant and, as middle income white households in particular moved to surrounding counties (City of Philadelphia 2011), poverty became increasingly racially segregated, with black residents concentrated in the most blighted city centre neighbourhoods. In this context, urban sustainability and particularly climate change have come to be seen as a new means through which the city might promote infrastructure renewal, redevelopment and economic growth.