Despite the frequent co-occurrence of alcohol and tobacco addiction, until recently little was known about the relationship between ethanol and nicotine. This compendium is based on presentations at a symposium held in 1994. Scientists at the conference were senior researchers concerned with co-occurrence of alcohol and tobacco dependence. They summarized the state of knowledge on a specific topic in their assigned domains and identify issues most in need of further investigation. The papers are in 2 sections: psychosocial and biological mechanisms of alcohol-tobacco use: and alcohol-tobacco use and dependence: treatment, early intervention, and policy. Illustrations.