Severe mental illness such as schizophrenia and mood disorders typically develops at a young age and can cause life-long disability. Currently available treatments cannot cure severe mental illness. This makes it important to find ways to prevent severe mental illness in young people before it has a chance to develop. This research study will pilot a new preventive intervention for young people who are at high risk of developing severe mental illness. The investigators will target early preceding factors (the 'antecedents') to severe mental illness which includes anxiety, unusual hearing and visual experiences, the loss of previously acquired abilities, and sudden and unpredictable changes in mood. These antecedents strongly predict an increased risk of developing severe mental illness. They are often impairing and distressing to the individual but can be improved with self-management skills and parent training, and they are present in the individual years before the onset of severe mental illness which makes them an ideal target for early intervention. The goal is to intervene early enough in the young person's life that severe mental illness can be prevented, hopefully leading to a happy, healthy and productive adulthood. The investigators want to test the acceptability and short-term efficacy of this new preventive intervention.