Implementing health promotion programmes in school settings(I.U.H.P.E. 2009; SHE network 2013; Safarjan et al. 2013; Simovska et al. 2011)is key to address health inequalities and improve children’s health and well-being. Nonetheless, the core business of schools is focused on educational outcomes, rather than the reduction of health problems. From an educational point of view, schools contribute to health by: i) creating the conditions for pupils’ achievement through improvement of the school environment; and ii) acquiring health competencies to empower young and future generations to make healthy decisions. Promoting health in schools means developing a policy at the school level, which remains difficult.As Don Nutbeam (2013) stated, despite “innovation, energy and enthusiasm, achieving successful implementation and sustaining the positive benefits for school students of school health programmes has proven to be challenging”. Achieving expected results in school settings is laborious and requires to understand discrepancies between expected and actual outcomes. Focusing on the implementation process itself is critical to inform potential further development of practice (Samdal & Rowling 2013). Such discrepancies are due to the embedded variability in contexts, which quite often differ from what had been foreseen during programme design, which to some extent, was undertaken out-of-context. When considering the variability embedded in contexts, it seems paradoxical to wish for and strive for programme fidelity, which in the end resembles more enforcement than it does co-construction, especially in multi-level and ecological approaches (Pettigrew et al. 2014). Instead, programmes may be considered added ingredients, “something extra” brought to and introduced to local ecology. When this added opportunity, or sometimes constraint, enters the context, interactions occur to result in short to long term outputs and outcomes on different levels of the local ecology (Trickett & Beehler 2013). Programme implementation is thus an enabling (or constraining) process towards a combination of expected achievements: (1) a potential impact on the targeted health issue; and potential outputs, i.e. (2) health capacity building, which materializes through the development of health-related actions and projects, and last butnot least, (3) settings’ and communities’ capacity to promote health, which includes the development of local level policy (St Leger & Young 2009). Our proposal is to understand and question the implementation process in school settings. The strong idea, and almost advocacy conveyed through this work, is the belief that a strong anchoring in the differences and potentialities of contexts has to also show in research designs. It is crucial to hope to upscale practice and provide support to professionals, starting where people are, and potentiating existing resources. For the purpose of acquiring a detailed and complex understanding of what is at play during implementation, the focus was set on what kind of outputs are created by the implementation of single programme over time, as well as what factors and combinations of factors can be deduced to influence implementation, from a long-term perspective. The format of this study is retrospective in order to capture potential outputs and processes that are not accessible on a short-term basis. Two types of outputs shall be considered: the development of health-related policy on a school level, and actions implemented by staff after participation to the programme; and potential health capacity building outputs. Three leads were undertaken for this research (1) pinpointing outputs of implementation on a staff and school level from a long-term perspective, and (2) understanding what key factors and combinations of key factors are involved in the effects observed, (3) and also identifying putative recurrences in combinations of contextual factors (Pommier et al. 2010).