The purpose of this webliography is to provide an overview of STEM education in the U.S. It provides easy access to research and best practices in the field, as well as specific programs, activities, and lesson plans that formal and informal educators can implement. The webliography also includes links to advocacy programs and resources for promoting STEM education and increased diversity in STEM fields. Resources were identified for this webliography based on the author's previous work as a librarian and educator in a natural history museum and her research in STEM and environmental education. Many of these web resources contain extensive databases and/or bibliographies, which led to the identification of additional resources to include here. Resources for this webliography were selected based on their currency and ability to provide a broad overview of the many facets of STEM education. In addition, only web sites with resources available for free, such as lesson plans, toolkits, and reports, were included. The first two sections of the webliography provide an overview of the current landscape of STEM education in both formal and informal educational environments. These resources highlight some of the challenges facing STEM education, its various benefits, potential avenues of collaboration to make STEM education more effective, and current research in STEM education. A third section highlights research on diversity in STEM, including organizations working to promote greater representation of women and minorities in STEM fields. The final section focuses on tools, such as hands-on activities, formal lesson plans, and assessment methods, that can be used to develop, deliver, and evaluate STEM educational programs.