This article addresses the role of a facility's process safety management system (PSMS) in preventing low probability-high consequence (LP-HC) accidents. We review the rationale for the hypothesis that a facility's PSMS is the central driver of accident prevention, and we discuss bow this rationale has been incorporated implicitly into the OSHA Process Safety Management standard (PSM) in 1992 and explicitly into both the EU Seveso II Directive and the USA EPA Risk Management Program regulation (RMP) in 1996. we then note that the limited process accident incidence data available to date have not resolved the issue of determining or predicting characteristics of a facility's PSMS that are likely to be effective in reducing LP-HC accidents. Based on a variety of considerations, the authors propose retrospective and prospective case-control studies on facilities with and without RMP reported process accidents using candidate survey instruments to test which survey factors appear to have the greatest prey dictive power for the likelihood of future LP-HC accidents. (c) 2006 American Institute of Chemical Engineers Process.