Atheist Alliance International is a global federation of atheist and freethought groups and individuals committed to educating its members and the public about atheism, secularism, and related issues, and to be a positive global voice for atheism and secularism.
Bay Area Humanists promote humanism -- an ethical, democratic, naturalistic life stance that prioritizes reason, scientific, and critical thinking -- as well as a system of humanist ethics and secular values as a rational alternative to ethics/values based on religion.
Bay Area Skeptics is one of the SF Bay Area's oldest and longest running science and skepticism organizations, promoting reason and critical thinking through regular meetings, SkepTalks, and social media.
Guerrilla Skepticism on Wikipedia editing team improves skeptical content on Wikipedia by improving pages of our skeptic spokespeople, providing noteworthy citations, and removing the unsourced claims from paranormal and pseudoscientific pages.
Independent Investigations Group is the local affiliate of an international network of trained investigators who will not only look into paranormal, fringe science, and extraordinary claims in their own regions, but also administer the IIG $100,000 Challenge.
Seti Institute is a private, nonprofit organization dedicated to scientific research, education, and public outreach; its mission is to explore, understand, and explain the origin, nature, and prevalence of life in the universe, through research in astrophysics, planetary science, and the search for extraterrestrial intelligence.
Stanislaus Humanists believe in doing good for its own sake. We're all about educating ourselves on how to make this world a better place, and we encourage and support each other in putting our knowledge into action.
Sunday Assembly Silicon Valley is a radically inclusive local branch of Sunday Assembly (featuring all the best bits of church without the religion) that celebrates life and welcomes all people, with or without faith, and supports everyone fulfilling their potential.
Wonderfest, the Bay Area Beacon of Science produces in-person and online science programs that stimulate curiosity, promote careful reasoning, challenge unexamined beliefs, and inspire life-long learning.