Procedures for systematic user involvement in primary mental health services are lacking, and several adolescents are dissatisfied with their opportunities to influence the service provided. The research on the effects of user involvement is scarce, especially regarding user involvement for children and adolescents. Hence, we suggest introducing an idiographic assessment tool in a selection of Norwegian primary mental health services. Idiographic assessment is a way of measuring psychological constructs, by using tools specifically adapted for each individual respondent.

This protocol describes the implementation and evaluation of a user involvement tool called 'Assert', in Norwegian primary mental health services. Assert is a simple tool where the adolescents themselves decide the goals or themes that they would like to address in collaboration with their service provider. Assert is scored each time the adolescent and the service provider meet, to monitor progress toward the goal. A randomised controlled trial design is proposed for this study. Assert will be implemented in 5-10 Norwegian municipalities, and will include 250 participants between 12 and 23 years. The objective of the study is to examine the relationship between Assert and perceived user involvement. Are idiographic measures an adequate way to operationalise user involvement on an individual level? And if so, can user involvement (i.e. Assert) have an effect on quality of life and mental health in adolescents? And lastly qualitative analyses of the adolescents' themes and goals will be conducted to explore what matters to the adolescents that visit primary mental health services in Norwegian municipalities.

Inclusion Criteria:

• Adolescents between 12 and 23 years, with behavioural, emotional, and psychosocial problems

Exclusion Criteria:

• severe psychopathological disorders
• severe drug addiction
• intellectual disabilities