Introduction and Aims: Antecedents of smoking have been widely researched in studies with older adults.However, less is known about the smoking patterns and antecedents of smoking in young adult smokers.

Design and Methods: In this study, we used ecological momentary assessment collected with an Internet-based survey instrument and used the participants’ own mobile phones to contrast the smoking patterns of young adult light and intermittent smokers (n = 23) with heavy smokers (n = 18).Overall, 1543 smoking and non-smoking situations were analysed. By means of generalised estimating equations, we used a range of situational characteristics to predict smoking in both groups.

Results: Craving and smoking of others increased the odds of smoking, and smoking bans were associated with a decreased probability of smoking among both light and intermittent smokers and heavy smokers. Situational antecedents differed between both groups. Cue-associated smoking played a bigger role for light and intermittent smokers than for heavy smokers. Situational antecedents, such as craving, being at the home of others, drinking alcohol and smoking by others,were more strongly associated with the smoking of light and intermittent smokers compared with heavy smokers.

Discussion and Conclusions: Smoking among young adults is associated with both internal and external situational characteristics. Compared with heavy smokers, light and intermittent smoking seems to be under more stimulus control and more characterised by social smoking.These results are consistent with several findings from previous studies and provide further information on different subgroups of smokers in early adulthood.