An estimated 800 000 suicide deaths occur worldwide. The global suicide rate is 11.4 per 100 000 population; 15.0/100 000 for males and 8.0/100 000 for females. Globally, suicide is the second leading cause of death in 15-29 year olds. In a collaborative effort to reduce the high rates of suicide and mental health problems among youth across Europe, the European Union 7th Framework funded the Saving and Empowering Young Lives in Europe (SEYLE) project. SEYLE is a randomized controlled trial (RCT) aimed to promote mental health and healthy lifestyles, while preventing psychopathology and suicidal behaviours among adolescents. The epidemiological data on 11,110 pupils in the age group 14-16 years, with a mean age of 14.8 years (SD ± 0.8), who were recruited from 168 schools across 10 European Union countries: Austria, Estonia, France, Germany, Hungary, Ireland, Italy, Romania, Slovenia and Spain, with Sweden as the coordinating centre showed the following prevalences: alcohol use (13.4%), smoking (30.9%), physical inactivity (32.8%), pathological Internet use (4.4%) and sleeping on average 7.7 hours per night. In terms of reproductive health, the prevalence of sexual debut was 18.8% for the total sample. Pupils aged .16 years had a higher prevalence (38%) of sexual debut compared to those aged .15 years (13.2%). Males had a higher prevalence (21.3%) than females (16.9%). Three clusters of adolescents were identified: 57.8% with low frequency of all risk-behaviours; 13.2% with high frequency of all risk behaviours; and 29% so-called ‘invisible’ risk group, which did not show any striking externalised riskbehaviours, but scored positive for high use of Internet/TV/videogames, sedentary behaviour and reduced sleep. When comparing pupils in the “invisible” risk group with those in the high-risk group, similar prevalence rates of anxiety (8% vs. 9.2%), subthreshold depression (33.2% vs. 34%), depression (13.4% vs. 14.7%) and suicidal thoughts (42.2% vs. 44%) were observed. Pupils meeting the criteria of depression and subthreshold depression were 10.5% and 32%, respectively. Prevalence rates for anxiety and subthreshold anxiety was 5.8% and 29.2%, respectively. Lifetime prevalence of deliberate self-injurious behaviours (D-SIB) was 27.6%, with higher rates reported for occasional D-SIB (19.7%) compared to repetitive D-SIB (7.8%). Suicidal ideation was present in approximately one third of the sample (32.3%). More than four percent (4.2%) of the sample reported attempting suicide during their lifetime, with a significantly higher prevalence among girls (5.1% vs. 3.0%, p<0.05). In comparing the effectiveness of the three active SEYLE interventions, based on three specific preventive strategies directed towards teachers and school staff, professionals and pupils in comparison to a control group, the intervention empowering pupils, called the Youth Aware of Mental Health (YAM) showed significant results in preventing new cases of suicide attempts, severe suicidal ideation with plans and depression. More than a 50% reduction of incident cases of suicide attempts (OR: 0.45 [0.24 – 0.85]; p=0.014), and of incident cases of severe suicidal ideation and plans (OR: 0.50 [0.27 – 0.92]; p=0.025), as well as a significant reduction by 30% of incident cases with moderate to severe depression (OR: 0.71 [0.52– 0.97]; p=0.031) was observed.