This report discusses the current knowledge on nicotine dependence, devoting a special chapter to smoking among youths, given that most smoking careers start in adolescence. The transition period, in which youths go from elementary to high school (ages 13-14), showes to be particularly risky for smoking initiation. The earlier youths start smoking, the more likely they will become dependent, and the more likely they will be heavier cigarette smokers in adult life. Since nicotine seems to be able to cause addiction in a short period of time, the aim should be to prevent children experimenting with cigarettes. Studies have shown that heavy smokers experience less aversive effects during their first smoke than light smokers. 'Light' cigarettes and flavour-enhancing additives could reduce aversive effects during smoking compared to regular cigarettes without such additives. Therefore, prohibiting the use of 'light' cigarettes and the use of flavour-enhancing additives could prevent adolescents from trying a second cigarette and ultimately contribute to preventing addiction among youths.