The social and economic impact of the Montreal Longitudinal and Experimental Study.

Background: The effectiveness of early prevention programmes and their viability as a public policy option have increasingly caught the attention of scholars and policymakers. Given the implementation costs of such programmes, it is important to assess whether they achieved anticipated objectives and whether they made efficient use of taxpayer money.

Aim: To discuss the social and economic impact of a 2-year randomised intervention aimed to improve social skills and self-control (i.e., non-cognitive skills) among disruptive boys from low-income neighbourhoods in Montreal.

Method: We review findings from published studies documenting the impact of the intervention at different stages of the life course, as well as its cost-effectiveness and cost-benefit.

Results: The intervention improved behavioural indicators throughout adolescence and eventually led to greater high school graduation rates, reduced crime, and better labour market outcomes in adulthood. Importantly, the prevention programme generated considerable returns to taxpayer investments.

Conclusion: Findings from the Montreal Longitudinal Experimental Study have been well-received and have contributed to an early prevention 'awakening' in Quebec and elsewhere.