Alcoholics Anonymous (AA) is the most prevalent 12-step mutual-help organization (MHO), yet debate has persisted clinically regarding whether patients whose primary substance is not alcohol should be referred to AA. Narcotics Anonymous (NA) was created as a more specific fit to enhance recovery from drug addiction; however, compared with AA, NA meetings are not as ubiquitous. Little is known about the effects of a mismatch between individuals' primary substance and MHOs, and whether any incongruence might result in a lower likelihood of continuation and benefit. More research would inform clinical recommendations.