Data from a nationally representative sample of US adults (n=42862) were used to explore the associations between drinking and smoking, on a lifetime and past-year basis, and between drinking and smoking cessation for a subsample of past-year smokers (n=12586). Smoking cessation was defined as current nonsmoking (as of the time of interview) that had lasted at least 3 months. The proportions of both lifetime and past-year smokers increased with volume of alcohol intake and frequency of heavy drinking and were greater for individuals with DSM-IV alcohol abuse or dependence than for individuals without these disorders. For example, the proportion of past-year smokers rose from 22.5% of lifetime abstainers to 53.0% of heavy drinkers, from 23.8% of those who never drank 5+ drinks on any drinking day to 61.8% of those who drank 5+ drinks weekly or more often and from 27.6% of individuals without past-year DSM-IV alcohol abuse or dependence to 55.5% of those with either of these disorders. The proportion of past-year smokers who had stopped smoking decreased from 7.8% of former drinkers to 4.6% of heavy drinkers, from 7.3% of those who never drank 5+ drinks to 3.4% of those who did so weekly or more often and from 6.7% among individuals without past-year abuse or dependence compared to 4.4% among those with either disorder. In a multivariate analysis that adjusted for background variables and smoking history, average daily ethanol intake was not significantly associated with the odds of smoking cessation, but drinking 5+ drinks at least once a month reduced the odds of cessation by 42%. Having an alcohol use disorder increased the odds of smoking cessation below the age of 30 (an effect that disappeared after adjusting for the interaction between age group and having children in the home), but had an increasingly negative effect on smoking cessation at older ages.