BACKGROUND: The prevalence of smoking is decreasing. At the same time, studies suggest that the relative proportion of nicotine dependent smokers is increasing. This may leave us with a smaller, but more problematic group of smokers. Few studies have investigated nicotine dependence in Norway. MATERIAL AND METHODS: Data were collected in the Young in Norway Longitudinal Study, where 2,890 respondents were followed up from their early teens until their late 20s. Information was collected on smoking habits, nicotine dependence, education, various indicators of social marginalization, anxiety, depression, suicidal behaviour, alcohol problems and use of drugs. RESULTS: At the age of 28 years, 12 % (n = 357) were classified as non-dependent daily smokers, whereas 5 % (n = 148) fulfilled criteria for "weak" and 3 % (n = 93) for "strong" nicotine dependence. 74 % of those who were in the "strong" dependent group at age 22 were still daily smokers at age 28; versus 50 % of non-dependent smokers. Nicotine dependence was associated with weak social resources, reduced mental health, alcohol problems and use of illegal drugs. INTERPRETATION: Daily smokers are more or less nicotine dependent. Smokers with a strong dependency have more stable smoking habits, weaker social resources and more problems with mental health, alcohol and drug use than others. Nicotine dependence represents a larger health political challenge for the authorities than previously recognised.