JUMP-in is a systematically developed intervention aimed at promoting physical activity among primary school children. It is a joint project involving different authorities and entails six school-based programme components. Measuring effects of such an intervention is a complex challenge. A common problem is the lack of valid instruments to measure physical activity and its determinants. In addition, it usually takes years to find improvements in physical activity and related constructs like weight and fitness, or even in causal factors. For this reason different authors advocate for the establishment of ‘health promotion outcomes’; (i) health literacy, (ii) social action and influence and (iii) healthy public policy and organizational practice. It is presumed that these health promotion outcomes lead to changes in determinants, behaviour and finally in health. Insight in these health promotion outcomes and information about input and through-put are important in discussing the impact and output. The formative evaluation study of the JUMP-in pilot shows the health promotion outcomes of the intervention. The health promotion outcomes ‘social action and influence’ and ‘healthy public policy and organizational practices’ were found to be positive. By measuring the presence of the conditions to achieve ‘health literacy’, it became clear that more attention must be paid to implementation in the future. Based on the health promotion outcomes, we expect that JUMP-in will be an effective intervention in the future.