Behavioural Development, Long-term Outcomes and Opportunities to Optimize Youth Mental Health (BLOOM) is a project that aims to overcome age and diagnostic boundaries to generate person-specific longitudinal profiles of mental health in youth aged 9 to 25. The overarching objective is to lay the informational foundation to accurately predict both clinical outcomes and opportunities to optimize health trajectories. This project will recruit youth in need without any mental health diagnosis and follow them annually for 5 years. The present study includes assessment of antecedents, opportunities and outcomes that will establish eligibility for preventive interventions