This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To identify and systematically review all mentoring interventions in all languages to prevent drug and alcohol use by children and adolescents. Control and comparison groups may have received no intervention, or the standard health education curriculum, or the alcohol and drug education curriculum normally used in the school or institution the adolescent attends, or individual counselling or support groups. The primary clinical outcomes are never starting to use drugs and alcohol or reduction in consumption.