Al-Anon: is a worldwide 12-step fellowship with a structure like Alcoholics Anonymous, but designed for loved ones, families, and friends of people with substance use disorder and/or who are in recovery. Al-Anon is open to anyone seeking support whether their loved one is in recovery or not, and their site has tools to find local meetings and other resources you may find helpful.
Alateen: is part of the fellowship of Al-Anon, and it is a program geared towards adolescents of families affected by substance use disorder. Their website has tools to find local meetings, events, and information/resources for adolescents.
NAMI Family Support Group: NAMI stands for the National Alliance on Mental Illness, and it provides broad support groups for family members of people with mental health conditions. Membership is free, and there is a weekly support group for adult family members as well.
Nar-Anon: is a 12-step fellowship similar to Al-Anon in structure, and it a community for loved ones of people with substance use disorder, in particular for narcotics. You can find a listing on their site for meetings and events near you.
SMART Recovery Family & Friends: SMART stands for Self-Management and Recovery Training, and it is a secular alternative to 12-step fellowships. On their site you can find meeting locations, online groups, meetings, and events.