There has been a dearth of epidemiological research on rates of mental disorder among Irish people and little is known about the numbers of young people in Ireland who are experiencing diagnosable mental disorders. In the context of such limited epidemiological research in the field of mental health, the PERL Group in the Royal College of Surgeons in Ireland has conducted two studies on mental disorders and psychopathology among young Irish people. This report is the first research report from these two studies by the PERL Group. It provides data on the prevalence rates of mental disorder, substance use, deliberate self-harm and suicidality among young Irish people aged 11-24 years.