The prime motivation for this report was to provide a basis for targeting development of the Building Regulations, the Housing Fitness Standard (HFS), and its successor, the Housing Health and Safety Rating System (HHSRS). However, the emphasis is on regulation in general, rather than specific legislation or guidance. The approach taken in the report has two key elements: - to summarise the evidence for the impact of buildings on human health and safety (throughout the report, safety includes fire safety); - to assess the relative importance of the various hazards in buildings, by applying the same risk assessment method to all. 147 pages.