The community-based 4-level-intervention concept developed within the “European Alliance against Depression” (http://www.eaad.net/) combines two important aims: to improve the care and treatment of patients with depression and to prevent suicidal behavior. It has been shown to be effective concerning the prevention of suicidal behavior [1–4] and is worldwide the most broadly implemented community-based intervention targeting depression and suicidal behavior. The 4-level intervention concept comprises training and support of primary care providers (level 1), a professional public relation campaign (level 2), training of community facilitators (teacher, priests, geriatric caregivers, pharmacists, journalists) (level 3), and support for self-help of patients with depression and for their relatives (level 4). In order to deepen the understanding of factors influencing the effectiveness of the intervention, a systematic implementation research and process analysis was performed within the EU-funded study “Optimizing Suicide Prevention Programs and Their Implementation in Europe” (http://www.ospi-europe.com/; 7th Framework Programme) [5]. These analyses were based on data from four intervention and four control regions from four European countries. In addition to intervention effects on suicidal behaviour, a variety of intermediate outcomes (e.g. changes in attitude or knowledge in different populations) were considered. Strong synergistic as well as catalytic effects were identified as a result of being active simultaneously at four different levels. Predictable and unpredictable obstacles to a successful implementation of such community-based programs will be discussed. Via the EAAD, the intervention concept and materials (available in eight different languages) are offered to interested region in and outside of Europe.