OBJECTIVES: We conducted a systematic review of the health impacts of housing improvement. METHODS: Forty-two bibliographic databases were searched for housing intervention studies from 1887 to 2007. Studies were appraised independently by H. T. and S. T. or E. S. for sources of bias. The data were tabulated and synthesized narratively, taking into account study quality. RESULTS: Forty-five relevant studies were identified. Improvements in general, respiratory, and mental health were reported following warmth improvement measures, but these health improvements varied across studies. Varied health impacts were reported following housing-led neighborhood renewal. Studies from the developing world suggest that provision of basic housing amenities may lead to reduced illness. There were few reports of adverse health impacts following housing improvement. Some studies reported that the housing improvement was associated with positive impacts on socioeconomic determinants of health. CONCLUSIONS: Housing improvements, especially warmth improvements, can generate health improvements; there is little evidence of detrimental health impacts. The potential for health benefits may depend on baseline housing conditions and careful targeting of the intervention. Investigation of socioeconomic impacts associated with housing improvement is needed to investigate the potential for longer-term health impacts.