Under the umbrella of the Healthy Futures Nearby programme, 46 small-scale projects were funded to promote changes in health-related behaviours (smoking, alcohol, diet and exercise) and to improve perceived health among vulnerable families in the Netherlands. The evaluation of these health-related multiple project programmes is often based on funder-defined outcomes and strategies. However, within the funded projects, assumptions about improving the health of vulnerable families based on local knowledge and experiences will also shape the project outcomes and strategies. These additional outcomes and strategies are project-specific interpretations of effective health promotion. Knowing these interpretations is crucial for the policy related and scientific relevance of the evaluation. Therefore, we aimed to determine the interpretations of each project and how they translate into relevant inputs for the overall evaluation of the programme. Based on 46 semi-structured group interviews with local project stakeholders, we produced a list of assumptions about what health promotion for vulnerable families should look like and then identified five main clusters: (i) strategies of offering pre-defined, health (behaviour)-related activities to families, (ii) actively involving vulnerable families in the initiative, (iii) assumptions about how health promotion should start with or include non-health-related topics, (iv) assumptions on how one should build on what already exists in the local context of the families and (v) assumptions on the role of the (health) professional in health promotion among vulnerable families. These project interpretations of effective health promotion provide inputs and priorities for the HFN programme’s overall evaluation.