There are dozens of organizations worldwide for alcoholics and addicts that base their recovery programs on the guiding principles of the 12-Step program originally advocated by Alcoholics Anonymous.
A few of these are:
More information is available at Wikipedia: List of Twelve Step Groups.
The largest of these, other than Alcoholics Anonymous, is Narcotics Anonymous (NA). NA was founded in 1953 and in 1972 it opened a World Service Office (WSO) in Los Angeles, California. According to its most recent membership survey, NA holds more than 61,800 weekly meetings in 129 countries. An excellent history of NA, co-authored by William L. White, is available here: Narcotics Anonymous: Its History and Culture.
These fellowships are identified with AA because they base their recovery programs on the 12 Steps and 12 Traditions of AA. As Narcotics Anonymous notes: “We follow the same path (as AA) with a single exception; our identification as addicts is all-inclusive with respect to any mood-changing, mind-altering substance.” (Narcotics Anonymous, p. xv)
The 12-Step program can be summarized as follows (Twelve-step program, Wikipedia)
admitting that one cannot control one’s addiction or compulsion;
- recognizing a higher power that can give strength;
- examining past errors with the help of a sponsor (experienced member);
- making amends for these errors;
- learning to live a new life with a new code of behavior;
- helping others who suffer from the same addictions or compulsions.
There is a good post on AA Agnostica about the 12 Steps here: The Origins of the 12 Steps. That post is also included in The Little Book: A Collection of Alternative 12 Steps.