Each of the interventions has elaborate and narrowly defined inclusion and exclusion criteria. These are listed below for each intervention.

'Signs of Internalizing'

Inclusion criteria

• Adolescents aged 12-17 years
• Mild to moderate impairment in daily functioning (e.g., reduced engagement in school, social life, or leisure activities compared to before symptoms)
• Adolescents with well-managed ADHD or autism may be included if they demonstrate sufficient mentalizing abilities and can benefit from the intervention with parental support
• Presence of both anxiety and depressive symptoms, neither of which dominates or meets full diagnostic criteria
• The family is motivated to participate

Exclusion criteria

• Symptoms of moderate to severe depression
• Presence of OCD, PTSD, agoraphobia, panic disorder, or other psychiatric conditions
• Low cognitive functioning
• Moderate to severe functional impairment (e.g., school dropout, extreme social withdrawal, daily reliance on adult support, lack of motivation for treatment)
• Recent unsuccessful psychological treatment
• Primary problems related to family dynamics or a highly burdened family situation
• Increased or acute suicide risk
• Presence of self-harm or symptoms of disordered eating

'Signs of Disordered Eating'

Inclusion criteria

• Children and adolescents aged 10-17 years
• High body dissatisfaction, preoccupation with food and/or body image, and/or early behavioral signs of an eating disorder
• Stable physical condition, manageable in consultation with the adolescent's general practitioner
• Able to consume food with guidance and support
• The family is motivated to participate

Exclusion criteria

• Previous treatment for an eating disorder
• Symptoms meeting criteria for specialized psychiatric treatment
• Low cognitive functioning
• Significant weight loss
• Solely restrictive or selective eating without other eating disorder symptoms
• Severe comorbidity
• Increased or acute suicide risk
• Eating difficulties solely related to lifestyle factors

'Signs of Self-Harm'

Inclusion criteria

• Adolescents aged 12-17 years
• Current thoughts of self-harm
• At least one episode of direct (non-suicidal) self-harm within the past three months
• The family is motivated to participate

Exclusion criteria

• Increased suicide risk
• Psychiatric disorder requiring further assessment or not adequately treated
• Low cognitive functioning
• Self-harm only in socially accepted contexts (e.g., piercings or tattoos)
• Only indirect self-harm (e.g., excessive substance use)
• Only self-harm by proxy (involving another person)

'Take the Control Back'

Inclusion criteria

• Children and adolescents aged 5-17 years
• Experiencing obsessive thoughts and/or compulsive behaviors of mild to moderate severity
• Experiencing self-perceived distress related to obsessive thoughts and/or compulsive behaviors
• Experiencing obsessive thoughts as egodystonic, and thus aware that they are excessive (for the youngest participants, this criterion may be waived in cases of limited insight)
• Functioning is impaired by obsessive thoughts and/or behaviors, e.g., reduced school functioning, social difficulties, or impaired functioning at home
• The family is motivated to participate

Exclusion criteria

• Symptoms meeting criteria for specialized psychiatric treatment
• Has another psychiatric disorder that requires assessment or is not adequately managed
• Has difficulties other than obsessive thoughts and behaviors that currently constitute the primary burden, and which must be addressed first
• Has previously received OCD treatment within psychiatric care (may be offered STIME if assessed but not treated due to mild severity)
• Has an increased or acute risk of suicide
• Has low functioning for other reasons, e.g., significantly reduced cognitive functioning

'the Parent Pilots'

Inclusion criteria

• Parents of children aged 3-10 years who experience developmentally inappropriate difficulties with restlessness, hyperactivity, attention, and/or impulsivity
• The symptoms must be present at home as a minimum, but may also occur across settings such as home, daycare, and school
• The child's difficulties must be significant enough to affect overall daily functioning
• The parents are motivated to participate

Exclusion Criteria:

• Symptoms of attention difficulties that require psychiatric treatment
• Presence of another psychiatric disorder that requires treatment
• Previous treatment for ADHD within the psychiatric system
• Low level of functioning due to other causes, such as significantly reduced cognitive functioning

History of severe allergic reactions to study medication Currently pregnant or breastfeeding Recent participation in another clinical trial within the last 30 days Presence of uncontrolled medical conditions that could affect safety