Brownfields are "abandoned, vacant, derelict or underutilized commercial and industrial properties where past actions have resulted in actual or perceived contamination" (NRTEE, 2003, p.1). Brownfield redevelopment, because of its contributions to urban sustainability, intensification and environmental quality, has become a critical issue in urban development literature of late. Through case-study research this paper aims to evaluate the relative sustainability of four Port Lands brownfield redevelopments that involve converting brownfields into green space in the City of Toronto. This study has shown how brownfield redevelopment and more specifically, turning brownfields into green space represent an application of all three pillars of sustainability. However, the exact extent of how this type of redevelopment represents an application of sustainable development cannot be truly measured or quantified. It has also highlighted the need to develop a comprehensive set of sustainability indicators that can be specifically applied to projects that aim to convert brownfields into green space.