Ethylene oxide is used as a fumigant in libraries and archives to control insect and fungal infestations that may damage library materials. While not widely used, ethylene oxide is the preferred means of pest control because it is effective against a wide variety of pests and has no deleterious effects on the components of library materials. This report summarizes information regarding ethylene oxide fumigation at libraries. Specifically, it describes methods of application, identifies target organisms, and estimates the current extent of ethylene oxide use at these facilities. Additionally, this report identifies currently available alternatives to ethylene oxide fumigation and discusses their benefits and limitations. Comparable cost information for ethylene oxide and alternatives is developed to assess the economic impact associated with cancellation of ethylene oxide registration. Additionally, costs associated with various registration options designed to minimize ethylene oxide exposure are estimated and the economic impact associated with such restricted use is developed.