There has been little discussion about how to apply population genetics methods to monitor the spread of transgenes that are detected outside the agricultural populations where they are deployed. Population geneticists have developed tools for analyzing the genetic makeup of individuals in hybrid zones, estimating migration and selection of genes, studying the influence of migration and selection on the shape of clines, and assaying the fitness of hybrids and backcrossed individuals. These tools may prove useful for monitoring the dynamics of escaped transgenes, but their effective application is likely to require access to information on the genetic makeup of transgenic organisms—information that is often proprietary. At present, depending on the jurisdiction involved, developers and regulators of transgenic organisms may be under no obligation to provide such information, thereby impeding independent public research of transgene escape and the refinement of methods used to study it.