The relationship between addiction medicine and addiction psychiatry is evolving. The increasing number of addiction medicine physicians will add their expertise to that of addiction psychiatry physicians to meet the growing demand of patients afflicted with an addiction disorder. Addiction medicine physicians, like addiction psychiatrists, also are involved in research and the education of other health care providers, and the education of the general public as well. The public health need is great. By working together addiction medicine and addiction psychiatry physicians can address this need far better than either can do independent of the other.