American Atheists : Works for the civil liberties of atheists, and the total, absolute separation of government and religion.
American Humanist Association : Promotes Humanism in the United States.
Americans United for the Separation of Church and State : Working on a wide range of pressing political and social issues.
Brights : Umbrella organization for people with a naturalistic world view.
Campus Freethought Alliance : Umbrella group for campus Freethought groups around the world.
Center For Inquiry West : West office for the Center For Inquiry in Amherst, NY, which houses Free Inquiry and Skeptical Enquirer magazines.
Council for Secular Humanism : Promoting reason, secular values, and the good life.
Darwin Foundation : The Charles Darwin Foundation is dedicated to the conservation of the Galapagos ecosystems
Freedom from Religion Foundation : Works to keep church and state separate, and to educate the public about the views of nontheists.
Gay and Lesbian Atheists and Humanists : American organization for gay, lesbian, bisexual, and transgendered atheists and humanists.
Gay and Lesbian Humanist Association : Provides a voice for the many non-religious in the lesbian and gay community. Based in the UK.
Humanists.net : National and International Humanist Societies
Humanist Society of Greater Phoenix : Provides speakers and meetings in the Phoenix Area
Positive Atheism : Discussing the history, ethics and philosophy of atheism promotes libertly, responsibility and peace of mind.
Religious Tolerance : Promotes religious tolerance as a basic human right.
Secular Student Alliance : Mobilizing students for a new Enlightenment.
The Skeptic Society : For anyone curious about controversial ideas, extraordinary claims, and the promotion of science. Publishers of Skeptic magazine.