The Skeptics Society is a scientific and educational organization that investigates fringe science and paranormal claims and strives to promote critical thinking. Michael Shermer is executive director, and he also serves as publisher of the group’s magazine, Skeptic.

The Robert Green Ingersoll Birthplace Museum in Dresden, N.Y., is described as America’s only freethought museum. It tells the story of the noted 19th-century agnostic orator, including his most famous speech, “Ghosts.”

The Richard Dawkins Foundation for Reason and Science supports “the scientific education, critical thinking and evidence-based understanding of the natural world in the quest to overcome religious fundamentalism, superstition, intolerance and human suffering.” The U.S. branch has headquarters in Washington, D.C., and is led by executive director R. Elisabeth Cornwell.

Project Reason is a nonprofit foundation dedicated to promoting secular values and scientific knowledge. Sam Harris is co-founder and chairman. Contact through the website.

The LGBT Humanist Council is a project of the American Humanist Association. It provides support to LGBT humanists in coming out and serves as a forum for exchanging ideas.

The Institute for the Study of Secularism in Society and Culture strives to foster understanding of the role of secular values and the process of secularization in today’s society. The nonpartisan, multidisciplinary institute is based at Trinity College in Hartford, Conn., and is part of the college’s Program on Public Values. Barry Kosmin is director.

The Institute for Science and Human Values is committed to scientific inquiry and the enhancement of human values and seeks to combine reason and compassion to achieve ethical wisdom. Toni Van Pelt is director of public policy.

The Humanist Society certifies humanist celebrants. It’s based in Washington, D.C. Sarah Ameigh is communications and policy assistant.

The Humanist Institute explores humanist values and trains future leaders. Its seminars are held primarily in New York City and Washington, D.C. Kendyl R. Gibbons and Carol Wintermute are co-deans of the institute. Contact through the website.