Current models of smoking and dependence assume a need to smoke at regular intervals to maintain nicotine levels, yet about 25% of adult smokers do not smoke daily. This subset of intermittent smokers (ITS) has gone largely unexamined. In this study, we describe the demographics, smoking history, and smoking behavior of ITS (n = 282; 50.2% male) in comparison to daily smokers (DS; n = 233; 60.7% male). Within ITS, we also compare "converted" ITS (CITS), who had previously smoked daily, with "native" ITS (NITS). On average, ITS were 34.66 years of age, and had smoked 42,850 cigarettes in the course of an average of 18 years of smoking. They smoked an average of 4.38 days per week, consuming 4.39 cigarettes a day on smoking days, and demonstrated considerable day-to-day variability in cigarette consumption. Almost half of ITS had Fagerstrom Test of Nicotine Dependence scores of 0, indicating no dependence. Compared to DS, ITS were more likely to cite alcohol drinking, socializing, and being with other smokers as common contexts for smoking, and they also more often cited being angry or stressed. Data suggested that ITS' behavior was not explained by use of other nicotine products nor by economic constraints on smoking, nor by differences in psychological adjustment. Within ITS, CITS were heavier, more frequent, and more dependent smokers. In many respects, CITS were intermediate between NITS and DS. ITS show distinct patterns of smoking behavior that are not well explained by current models of nicotine dependence.