This project set out to assess the extent of protection for passenger car occupants involved in side impact collisions in this country and to make recommendations of ways in which this protection could be improved. A review of the international literature was initially undertaken to highlight current worldwide issues and deliberations and discussions were held with a number of overseas experts on regulation developments in Europe and the U.S.A. A case series study of 198 crashed vehicles involving 234 injured occupants was then carried out involving post-1982 passenger cars and derivatives in side crashes where at least one occupant was either hospitalised or killed in the crash. Details were collected on the extent of deformation and intrusion from the crash, the estimated change of velocity during impact (delta-V), the injuries sustained by the occupant(s) and the sources of these injuries from inside or outside the vehicle. This report describes the findings from this research and makes recommendations of a range of suitable countermeasures to reduce teh incidence and severity of these injuries. The relevance of planned side impact performance regulations in the U.S.A. and Europe is also considered to the extent possible at this time. A supplementary volume provides a case-by-case summary of each crashed vehicle inspected.