Like most U.S. chemical companies, you probably know where your security-sensitive inventories are located within your sites and have assured yourself that you have taken reasonable precautions to reduce the risk of their being used in a terrorist attack. What about when you ship them? How secure are the various parts of your value chain - offsite storage and transportation of your products, raw materials, intermediates, and wastes, and processing of ordering and invoicing transactions? Value chain security focuses on tampering and misuse of materials handled outside the plant boundaries. At FMC, we took a three-stage approach to identifying and dealing with potential security issues posed by materials in transit. Stage 1 was a quick review to determine which of our products, intermediates, or raw materials might be potentially useful to terrorists. In Stage 2 we looked for specific security-emergency scenarios that might involve those chemicals, estimated the risk of those scenarios, and made recommendations to reduce the vulnerability to terrorist attack. In Stage 3 we are implementing the plans we developed. FMC's approach has successfully focused our efforts and used familiar techniques to break down complex Value Chains into manageable sections and then to identify. the possible scenarios and (relative) risks at each section. We were able to do this with minimal travel costs. This paper describes the general organization of FMC's value chain security efforts and our analysis technique, and discusses lessons (including a few surprises) that we have learned from the analyses. (C) 2005 American Institute of Chemical Engineers.