Skeptical Inquirer (S.I.) is a bimonthly American general-audience magazine published by the Committee for Skeptical Inquiry (CSI) with the subtitle "The Magazine for Science and Reason". The magazine initially focused on investigating claims of the paranormal, but evolved and expanded to address other pseudoscientific topics that are antithetical to critical thinking and science. Notable skeptics have credited the magazine in influencing their development of scientific skepticism. In the "Letters to the Editor", the most frequent letters of appreciation come from educators.

The magazine was originally titled The Zetetic (from the Greek meaning "skeptical seeker" or "inquiring skeptic"), and was originally edited by Marcello Truzzi. About a year after its inception a schism developed between the editor Truzzi and the rest of the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP). CSICOP was more "firmly opposed to nonsense, more willing to go on the offensive and to attack supernatural claims" while Truzzi wanted science and pseudoscience to exist "happily together". Founder Paul Kurtz strongly believed "it's important that, when claims of the paranormal get wide public attention and belief, the skeptical position also get media attention". Truzzi resigned to start The Zetetic Scholar and CSICOP changed the magazine's name to Skeptical Inquirer and hired Kendrick Frazier as the new editor.

The first issue of S.I. was Fall/Winter 1976. In 1995, S.I. changed format from digest size to a standard magazine size, increased the publication frequency from quarterly to bimonthly, and added newsstand circulation in addition to subscription.

In 2013, writer and skeptic Daniel Loxton posited that if Skeptical Inquirer was not the first skeptical publication, it is yet considered the "'birth of modern skepticism' (at least for the English-speaking world)" because CSICOP organized "this scholarship collectively [and] comprised a distinct field of study", and was the first to establish "best practices... specialist experts... buildings... periodicals and professional writers and researchers".

Barry Karr is the executive director of CSI and Skeptical Inquirer. In June 2023, Stephen Hupp, a professor in the Department of Psychology at Southern Illinois University Edwardsville, was named as the magazine's editor. Hupp replaced Stuart Vyse, who was the interim editor in November 2022 following the passing of Kendrick Frazier.

In 2025, as a way to be more inclusive, Skeptical Inquirer launched an audio version of the magazine, available on several podcast sites.

The Committee for Skeptical Inquiry functions as a scientific society and, upon editorial acceptance, publishes articles from independent scientists and investigators in the Skeptical Inquirer. Published topics have included fringe science, pseudoscience, paranormalism, psychic phenomena, astrology, ufology, homeopathy, and New Age, as well as articles on politics, general science, cyberterrorism, and others. Writing for Scientific American in 1982, cognitive scientist Douglas Hofstadter said that the purpose of Skeptical Inquirer was to "combat nonsense" with articles in English that require no special knowledge or expertise, only "curiosity about truth".

Loxton, writing in 2013 about the mission and goals of the skeptical movement, countered the idea that people no longer wanted to read about the paranormal, and recommended getting back to S.I.'s basics. Paul Kurtz in 2009 seemed to share this sentiment and stated that the organization would still research some paranormal subjects as they have expertise in this area, but they would begin to investigate other areas. "CSICOP has reached an historic juncture: the recognition that there is a critical need to change our direction", Kurtz wrote. While editor Kendrick Frazier did expand the scope of the magazine to include more topics on subjects that attacked science or critical thinking—such as climate change denialism, conspiracy theories and the influence of the alternative medicine movement—Frazier also noted that "paranormal beliefs are still widespread", and quoted surveys that state that the public, given a list of ten general paranormal topics, will select four as topics they believe in. While the general skeptic community believes that we should not waste more time debunking the paranormal, topics long ago discredited, Frazier says "millions of Americans accept them today". Even with such long odds against "an organized paranormal lobby, a magical marketing machine", Loxton implores skeptics to continue researching, writing and publishing: "We can't win any ultimate victory over superstition or ignorance, but we can do a lot of good if we fight hard enough."