Proponents of genetically engineered (GE) crops often assume that the risk management used in the industrial world is appropriate for small-scale, traditionally based agriculture in the Third World.  Opponents of GE crops often assume that risk management is inappropriate for the Third World, because it is inherently biased in favor of the industrial world.  We examine both of these assumptions, by rethinking risk management for GE crops and transgenes, using the example of maize transgene flow from the U.S. to Mexico.  Risk management for the Third World is a necessary first step of a broader benefit?cost analysis of GE crops, which would include comparisons with existing varieties and with alternative varieties such as transgenic farmer varieties and organic varieties.  Our goal is to use existing information on GE crops and on the social and biological characteristics of Third World agriculture to identify key processes that need to be considered in risk management, and the additional research required to adequately understand them.  The four main steps in risk management are hazard identification, risk analysis (exposure x harm), risk evaluation, and risk treatment.  We use informal event trees to identify possible exposure to GE crops and transgenes, and resulting biological and social harm; give examples of farmers' ability to evaluate social harm; and discuss the possibilities for risk treatment.  We conclude that risk management is relevant for Third World agriculture, but needs to be based on the unique biological and social characteristics of small-scale, traditionally based agriculture, including the knowledge and values of Third World farmers and consumers.