The best known support group is Alcoholic Anonymous. This group known as AA follows the traditional 12 step program. Information on this group can be found at:

http://www.aa.org/

http://www.aacanada.com/
AA is not the only support group available for Alcoholics. An alternative that does not follow the 12 step program is
http://www.smartrecovery.org/
Alcoholics are not the only people who require support. Usually friends and family are also affected by the addiction of a loved one. A well known support group for such individuals is Al-Anon
http://www.al-anon.alateen.org/