Substance misuse in young people ranges from readily available and legal substances such as tobacco, alcohol, synthetic drugs and volatile substances to more uncommon and illegal substances such as Ecstasy, cannabis, synthetic drugs, cocaine or heroin. Many young people will experiment with alcohol and/or illegal drugs and for a small minority of young people, the use of alcohol and/or illegal drugs will escalate into addiction. One of the key characteristics of substance use among young people involves the ‘Gateway’ or ‘Escalation’ theory, that is the progression from one psychoactive substance to another. For example, having used one substance (e.g. cigarettes) is linked with experimentation with another (e.g. cannabis). There is evidence to suggest that among both early school leavers and students attending school, having tried cigarettes was a strong predictor of drinking alcohol and using cannabis. Parental influences have a significant influence on the drinking culture of their children. It is acknowledged that parental alcohol use increases the risk of initiation and the intensity of later adolescent alcohol use. There are relatively well established associations between several risk and protective factors and problematic drug use among young people.