A great deal is now known about early risk factors for delinquency and later criminal offending. These can be at the individual, family or environmental levels. Individual-based prevention programmes target risk factors for delinquency and later offending located within the individual. These interventions focus directly on the person and can be implemented very early in life, for example, cognitively based preschool education. Systematic and meta-analytic reviews find that two main types of individual-based programmes, which include preschool intellectual enrichment and child skills training, are generally effective in preventing delinquency or later criminal offending. A recent meta-analysis found that two main types of family-based programmes, which include general parent education and parent management training, are effective in preventing delinquency or later criminal offending. The most effective programmes in preventing delinquency and related behaviour problems (that is, aggressive or violent behaviour) were those that targeted the highest-risk students.