The 2016 United Nations (UN) New Urban Agenda clearly reaffirms the concept that sustainable cities require intertwined environmental and social sustainability. The United Nations Sustainable Development Goal (SDG) 11—“Make cities inclusive, safe, resilient, and sustainable”—sets (as a primary target) the provision of sufficient affordable housing. Despite the central role that housing plays in ensuring sustainability and the importance of both environmental and social pillars in ensuring sustainable development, current evaluative methods that support decision making on social housing interventions fail to capture all of the socio-environmental value contained in the UN SDG 11. This paper addresses the issue by demonstrating how Sustainable Return on Investment can successfully describe and analyse a range of externalities related to the sustainable value generated by social housing regeneration schemes. To achieve this goal, a single case study strategy has been chosen. Two extant projects—a high-rise housing scheme and an environmental-led program developed by City West Housing Trust (a nonprofit housing association based in the Manchester area)—have been assessed in order to monetise their social and environmental value through different methods. The findings show that, historically, the environmental and social value of regeneration schemes have been largely disregarded because of a gap in the evaluation methods, and that there is room for significant improvement for future evaluation exercises.