Aim. To compare and contrast those SI pupils in Scotland (typically age 11 to 12) who have initiated illegal drug use with their non-illegal drug using peers. Design. Self-completion school surveys totaling 930 SI pupils. Setting. Dundee, Perth and Kinross, and Lanarkshire, Scotland. Findings. This research has identified that approximately one in ten SI pupils have already initiated illegal drug use in Scotland. Young people who reported using illegal drugs at this early age tended to have started smoking and drinking alcohol at an earlier age than their non-illegal drug using peers and to be both smoking and drinking alcohol at a higher level than those peers. The illegal drug using pupils were much more likely than their peers to have been exposed to illegal drugs, to have been involved in a range of problem behaviours and to have friends who were also involved in a range of problem behaviours. The illegal drug using young people were also much more likely to have someone in their family who was also using illegal drugs. Conclusions. There is a need to target interventions upon those young people who have initiated illegal drug use at this early age, however doing so is unlikely to be straightforward. It is suggested that there may be some merit in using an “at-risk” type register to focus upon those young people at particularly high risk of initiating illegal drug use.