In this study we examined the interdependence of a broad range of sociodemographic characteristics in a large sample of 15-year-old smokers and nonsmokers. The most prominent risk factors for smoking included the father figure not being the natural father, low family SES, and the young person having a recent part-time job. In particular, the number of adverse sociodemographic conditions present was associated with an increased likelihood of daily smoking at ages 15 and 18. It is estimated that over a 1-year period the cost of cigarettes consumed by 15-year-olds alone is NZ$4.6 million. Use of sociodemographic characteristics to target adolescents at risk of becoming smokers is discussed.