This study focused on the duration of participation in professional treatment and Alcoholics Anonymous (AA) for previously untreated individuals with alcohol use disorders. These individuals were surveyed at baseline and 1 year, 3 years, 8 years, and 16 years later. Compared with individuals who remained untreated, individuals who obtained 27 weeks or more of treatment in the first year after seeking help had better 16-year alcohol-related outcomes. Similarly, individuals who participated in AA for 27 weeks or more had better 16-year outcomes. Subsequent AA involvement was also associated with better 16-year outcomes, but this was not true of subsequent treatment. Some of the association between treatment and long-term alcohol-related outcomes appears to be due to participation in AA.