Alcoholics Anonymous ( AA ) is a global peer-led mutual aid fellowship begun in the U.S. and dedicated to abstinence-based recovery from alcoholism through their spiritually inclined twelve-step program. Besides stressing anonymity and offering membership to anyone wishing to stop drinking, AA's twelve traditions establish it as free to all, non-professional, non- denominational, apolitical and unaffiliated. In 2020 AA estimated its worldwide membership to be over two million with 75% of those in the U.S. and Canada.

In 1935, the recognized start of AA, Bill Wilson (Bill W.) first commiserated alcoholic-to-alcoholic with Bob Smith (Dr. Bob). Meeting through AA's immediate precursor the Christian revivalist Oxford Group, they and other alcoholics fellowshipped there until forming what became AA. In 1939 the new fellowship, then mostly male and white, published Alcoholics Anonymous: The Story of How More Than One Hundred Men Have Recovered From Alcoholism, also known as the Big Book and as the source of AA’s name.

AA's twelve steps are a suggested and continuing sobriety program of prayer, reflection, admission, better conduct and atonement, all to effect a “spiritual awakening”, after which members should take others through the steps, usually by taking on sponsees. Divining and following the will of an undefined God—"as we understood Him", also designated as a “higher power”—is integral to the steps, but differing practices and beliefs, including those of atheists and other non-theists, are accommodated.

The twelve traditions are guidelines to keep AA focused on altruistically helping others to recover from alcoholism. With AA's traditions membership goes to anyone professing a desire to stop drinking, and that all memberships should be kept anonymous, especially in public media, but no repercussions are prescribed for broken anonymity. Additionally the traditions have AA avoiding hierarchies, dogma, public controversies and other outside entanglements, or using AA for personal gain or public prestige. They also insist that no dues or fees are required, and to be self-supporting, no outside financial aid can be accepted.

In 2020 a scientific review found that clinical interventions increasing AA participation via AA Twelve Step Facilitation (AA/TSF) had sustained remission rates 20-60% better than other well-established treatments regardless of demographics. Additionally, 4 of the 5 economic studies in the review found that AA/TSF lowered healthcare costs considerably. Regarding the disease model of alcoholism, an otherwise receptive AA has not endorsed it while many AA members have promoted it towards wider acceptance.

AA has allowed other recovery fellowships such as Narcotics Anonymous and Al- Anon to adopt and adapt the twelve steps and twelve traditions.