Each year 11.2% of the Dutch adolescents have suicidal thoughts and 6.6% attempt suicide or engage in deliberate self-harm. In this age group suicidal behaviors (suicidal thoughts, deliberate self-harm and suicide attempts) are closely linked to depression and it is known that both the incidence of depression and suicidal behaviors increase dramatically during adolescence. We will test and, if effective, implement a multimodal stepped-prevention program with suicidal ideation as the primary outcome and depression as the secondary outcome. The stepped prevention is directed at 16-21 year olds in the first and second grades of higher vocational education (ROCs) in the region of North-East Brabant. Choosing this school type is important because it guarantees that the intervention will be delivered to students of predominantly lower social economic status and from diverse ethnic and cultural backgrounds. The multimodal prevention program is designed to significantly reduce suicidal ideation and depression in ROC students. The program consists of four integrated components: (1) gatekeepers training (aimed at professionals to create a safety-net at the ROC schools), (2) universal prevention (to reduce stigma and increase mental health literacy in all ROC students), (3) screening (for the detection of students who suffer from early symptoms of suicidal depression and need a more intensive intervention), and (4) indicated depression prevention (which is CBT-based and offered to positively screened students). Each of the distinct components is theory-based and finds empirical support in both national and international studies, but their combined effectiveness has not been evaluated before. Through intensive, structural collaboration between municipality health services, schools, mental health services and national research institutes, we create an outstanding infrastructure for evaluation and implementation of the preventive program if proven effective and scaling up is warranted.