I - INTRODUCTION: Prioritizing health inequalities reduction emphasizes the relevance of targeting health determinants in public health interventions. The school, as a focal point in communities, offers great potential for such interventions, thus endorsing a crucial role in implementing public health strategies on an international(Marmot, 2011)or national level, with for example the National Health Strategy in France(Cordier et al., 2013). In French schools, the policies implemented are consistent with a health promoting approach, focusing on academic achievements for all and citizenship (MEN, 1998), thus calling for project management, credentialing of all stakeholders and new partnerships (MEN, 2011). The preceding Health Education Policy coherently follows up from the National Health Policy and is integrated in school projects as formalized on an academy level (MEN 2011). Health Education exists in the French Educational System as a transversal entity associating clearly defined content such as clear health education learning objectives within existing academic disciplines (e.g. developing social and citizenship competency), associated with more implicit objectives such as working on common values, social and physical environment management, collective work. Teacher training has been strengthened, development of health education related competencies made evident in concurrently structured of policies (MEN 2013). In practice, policies are implemented through programmes and projects which also impact professional practice development in health education. Nevertheless, one cannot fail to observe, that implementation of health promoting policies sometimes proves difficult on a school level (IUHPE, 2010), and on a professional level, especially among teachers. As stated in the literature, in schools, professional practices are heterogeneous due to difficulties in grasping what is at stake in health education. Among the potential factors impacting health education practice, one may distinguish from institutional, professional, personal and contextual factors(Simar & Jourdan, 2010), the very context of the school also proving critical (Guével, Pommier, Jourdan, D., 2013). Programmes based on support and professional training tend to be more efficient, as long as training is sufficiently intensive and consistent with professional identity and core activities(Simar & Jourdan, 2010). While “one shot” interventions, unique and/or isolated actions prove little efficacy, programmes adapted to context-specifics(Stewart-Brown, 2006), based on transdisciplinary coalitions(Kegler, Steckler, Malek, McLeroy, 1998)engaged in collaboration which includes the community as a partner(Dempsey, Barry, Battel-Kirk, and the CompHp project partners, 2011)show greater relevance(St Leger, Young, 2009). Based on these conclusions, the arising question focuses on how academic level health policies, which include implementation of health promotion programmes, amongst other things, impact school health promoting dynamics in terms of what is carried out in actual facts? This retrospective study on a 10 year period aims at understanding how a health policy is structured on the level of an academy, as well as how it may have an impact on health promotion implementation dynamics on a school level. II THEORETICAL PERSPECTIVE: Our perspective thus draws on system-thinking(Glasgow, Lichtenstein, Marcus, 2003)and complexity theory(Gatrell, 2005)to focus and consider the potential contextual factors which impact professional practice in health promotion and may repercuss on the adoption of a programme and its sustainability. Among the potential factors that have been identified on a theoretical level, policy-related factors, programme-related factors, asreference prescriptive guidelineswill be explored, bearing in mind professionals’ individuality and creativity as well as how missions and tasks are redefined and carried out(J. Leplat, 2000)accordinglyThe aim of this study is consequently to explore the complex contextual factors linked to policy and programme implementation (macro level), completed with the understanding of their potential impact on the school itself, (micro and meso levels)(Glasgow, Lichtenstein, Marcus; 2003). Method III METHODS: This research is based on a three-study design focusing on three case-studies (Yin, 2009) based on professionals implementing a health promoting project in school settings, in variable time-frames, scales and levels of complexity. The first study aims at providing a retrospective overview of the potential factors identified in an initial programme theory elaborated in a realistic evaluation framework » (Pawson, Tilley, 2004). Data collection is ongoing and involves 2 schools that have been exposed to a healthy eating programme in different timeframes over a ten year period, thus taking into account variability in public health policies. Data collection focuses on the contextual factors in play in initial project elaboration, its adaptation in time, its adoption by professionals and stakeholders and finally its sustainability. Interviews with the project managing team, project document analysis are used to elicit and identify critical context-specific and professional-specific factors in a complex and dynamic perspective. Focus groups will be organized in the selected schools involved in the project in the last ten years to focus on collective work, sustainability and potential retroactions on the project. Expected Outcomes IV EXPECTED OUTCOMES: In analyzing the results, we expect to conceptualize the complex interactions between micro, meso and macro contextual moderating factors and their impact on professional practice and project implementation and sustainability in the field of school-based health promotion. The focus on school professionals exposed to the programmes at the initial elaboration phase of the programme (t), as well as at a later stage of evolution (t plus 10 years) already points out variability in impact of the programme, and also sustainability. In analyzing the data collected, we intend to elaborate a typology of impacts and pinpoint the corresponding modulating factors. This will lead to designing a framework for support to professional practice based on adaptation and potentiating of action in specific contexts. Potential recommendations for policy-making may also be drawn in a bottom-up perspective. V FOCUS OF THE COMMUNICATION PROPOSAL: This publication aims firstly at presenting the overall theoretical standpoint in the first study of our research framework in exposing the results of the currently ongoing retrospective study. First results from the other two studies will be briefly presented to broaden the perspective.