In this paper we report the results of research on the nature and extent of legal and illegal drug use among preteens and those factors associated with illegal drug use at this young age. The paper is based upon a survey of 2318 ten to twelve year olds in Glasgow and Newcastle. Overall around 30% of children reported having been exposed to illegal drugs and 3.9% had started to use illegal drugs. There was a significant difference in the level of illegal drug use between our two cities. In most cases the illegal drug use identified on the part of preteens related to cannabis although in a small number of instances children were using heroin, cocaine and LSD. On the basis of this research we estimate that around 60 children in the ten to twelve age range will have used heroin in Glasgow and around 34 pupils will have used the drug in Newcastle. Preteen drug use was significantly associated with frequent smoking and alcohol consumption, with preteens' involvement in a range of problem behaviours, and with family difficulties including the presence of someone else within the family using illegal drugs. The paper concludes by noting some of the challenges that are likely to be faced by services seeking to support children who are using illegal drugs by their preteens.