The Regional Breeders Testing Network (RBTN) is a trial designed to provide public cotton breeders easy access to multi-environment testing of advanced breeding lines.  A wide range of environments ranging from Louisiana to Arizona are represented in the RBTN.  The value of an environment for evaluating breeding lines is often measured in terms of the average yield for a location.  An environment producing a low average yield is often considered less valuable when compared to a high yielding environment.  However, the ability to discriminate among genotypes would be a better measure of the value of an environment.  Analysis of RBTN data using GGE biplot is used to show the relationships among test environments and compare discriminating ability of RBTN environments.  Information should prove useful in the planning and selection of environments for the RBTN program.