BACKGROUND: Online interventions to prevent mental health problems have proven to be effective. However, knowledge about their implementation in real-world practice as well as for dissemination to the target groups in different settings is scarce. The goal of the 'ICare' network is to establish a comprehensive model of eMental-health service delivery in and across different European countries. Since implementation and dissemination are influenced by many contextual factors, in the first phase of ICare a stakeholder survey was conducted. The survey aim was to explore stakeholders' experiences, needs and attitudes regarding Internet-based prevention of mental health problems and hindering and fostering factors for implementation and dissemination. This article is part of a supplement and describes the design of the stakeholder survey. Survey results are published in separate articles in the same supplement. METHODS: Based on a literature review and the individual characteristics of the ICare interventions, stakeholder groups were identified in different settings across six European countries. The RE-AIM framework guided the development of the research questions and survey instruments. A concurrent mixed methods design was applied comprising focus groups with the intended target groups of ICare interventions, an online questionnaire with potential facilitators/delivery staff and semi-structured interviews with policy makers. CONCLUSION: The challenge was to develop a design that allowed flexibility but at the same did not jeopardize the validity of the study. Implications drawn from this survey are not restricted to specific preventive interventions but will provide general information on how online mental illness prevention can be best implemented in various settings.