This study examined the extent to which tobacco dependence (TD) and alcohol use disorders (AUDs) reciprocally influenced each other in a mixed-gender sample of 452 individuals (n= 232 biological family history of paternal alcoholism, n= 220 no first- or second-degree family history of alcoholism) who were assessed once early in their freshman year of college, ∼3 years later when many were college seniors, and ∼3 years later when many had entered or were entering the work force. AUDs were more prevalent in men than women, in individuals with a family history of alcoholism, and decreased overall with time. TD was more prevalent in those with a family history of alcoholism, showed increasing rates of use over time, and was less prevalent but more stable than AUDs. Transitional probabilities indicated that although a previous AUD or TD diagnosis increased the likelihood of being diagnosed with the other disorder at a later time, comorbid AUDs and TD did not significantly affect the likelihood of recovery from either disorder. Finally, path analysis revealed significant reciprocal relationships between AUDs and TD diagnoses (each predicting the other over time), and significant prediction of AUDs and TD by family history of alcoholism at the first and third times of assessment. Findings supported two general models of AUD/TD comorbidity: a shared vulnerability model and a reciprocal influence model.