The housing needs of low-income families occur in the context of the larger private housing market, a market which has been profoundly influenced by government policies. The recent housing boom and bust has left policymakers struggling to understand and address unprecedented challenges, while longer term problems are presenting themselves on the horizon. This What Works Collaborative framing paper focuses on four pressing housing policy challenges and the research needed to address them: the long-term damage stemming from the housing crisis; rising poverty coupled with high income inequality and volatility; persistent concentration of poor and minority households in low-quality housing and low-opportunity neighborhoods; and the need for environmentally sustainable buildings and communities. This framing paper is part of a series of field-building research agendas produced under the What Works Collaborative. More information can be found on the What Works Collaborative web page