This paper outlines the rationale for an affordable housing strategy, both, for equity and the environment. This paper argues that housing affordability must be included in any discussion on environmental sustainability. Failure to ensure affordable housing will mean increased transportation costs, and greenhouse gas emissions, as families seek affordable housing further away from the central city. Moreover, while many in North America argue that more density, more housing supply and a mixed, diverse housing will lead to greater affordability, the evidence in Vancouver is not consistent with these premises. As will be shown in this paper, it is the lack of affordability due to rising land values that is driving greater densification.