In this project, NCHRP 25-27-- Evaluation of the Use and Effectiveness of Wildlife Crossings, our charge was to provide clearly written guidelines for the selection, configuration, and location of crossing types, as well suggestions for the monitoring and evaluation of crossing effectiveness, and their maintenance. The guidelines were developed especially for transportation planners and engineers, as well as for wildlife ecologists. They are presented in the form of a final report and a web-based interactive decision guide. We conducted 7 integrated research efforts as part of this report. They included a North American telephone survey on the state of the practice and research of wildlife crossings, a continent-wide list of priority actions needed for practice and research, a safety research analysis of wildlife vehicle collisions that included the development of safety performance functions and an analysis of differences obtained when using WVC data vs. deer carcass data, an accuracy modeling effort that involved the relative importance of spatially accurate data, an analysis that investigated the usefulness of different kinds of GIS-based clustering techniques to detect hotspots of wildlife killed on roads, a field study of small mammals conducted in Utah and in British Columbia that investigated the putative habitat degradation effects of roads, and an investigation into allometric methods to effectively place wildlife crossings to increase habitat permeability. The interactive decision guide can be found at the URL: http://wildlifeandroads.org. Results of a literature search and other components of this project can also be accessed at this site through an interactive search engine.