The forty years of the Loss Prevention Symposium has paralleled the careers of several of us in the loss prevention profession. During this time period, at the Dow Chemical Company, Rohm and Haas, and many chemical companies, the role of the loss prevention professional (LPP) has expanded from a concern for fire protection engineering to a more proactive concern for process hazards and process safety management. The role of the LPP has changed primarily because of lessons learned from major chemical processing incidents that have occurred. The Loss Prevention Symposium has served as a forum for discussing these incidents and related process safety technology. For example, Flixborough (1974) demonstrated the concern for large quantities of flammable material in the process. Seveso (1976) demonstrated the necessity to review processes for reactive chemical potentials. Mexico City (1984) illustrated the hazard of large inventories of flammables, the consequences of inadequate separation distances, and the need for adequate firewater supply. Bhopal (1984) clearly emphasized the need to evaluate processes for large toxic inventories that could be released and cause harm to large populations. Pasadena (1989) reemphasized the hazards of large inventories of flammables. In 2003, the U.S. Chemical Safety Board investigated several serious dust explosion incidents that have awakened industry to the hazards of combustible dusts. The March 2005 Texas City refinery explosion has highlighted concerns for facility siting and the hazards of start-up operations. Because the root causes of all these incidents were management system deficiencies, the current role of the LPP now focuses on the evaluation of process safety management systems as well as the evaluation of process hazards. The need for a positive safety culture to successfully implement process safety management systems has recently been recognized. This article will explore the effects of major chemical incidents on the role of the LPP past, present, and future. (c) 2006 American Institute of Chemical Engineers.