The new urbanism promotes preferred design and land use patterns as a means to enhance quality of life through socioeconomic diversity, but many criticise these assertions of causality. Deriving community indicators for social sustainability – including housing affordability and socioeconomic diversity – and from studies assessing new urbanism as an infill development tool, we examine the impact of new urbanism infill development in Parramore, an economically distressed inner city neighbourhood, and Baldwin Park, a brownfield inner-ring suburb, with comparative control neighbourhoods in Orlando, Florida. In Parramore, active new urbanism implementation, including HOPE VI and the Partnership for Sustainable Communities, reflect revitalisation efforts through increased socioeconomic diversity. Meanwhile, the Baldwin Park plan incorporates many new urbanist best practices. The findings from these two distinct cases of infill development indicate that the new urbanism does not necessarily ensure social sustainability, though these principles are often integrated into publicly funded revitalisation initiatives dedicated to doing so through mixed use and mixed income development.