Existing studies on complex interventions aiming to promote youths’ participation in physical education (PE) appear to be predominantly single-methodological. The aim of this article is to examine the benefits and challenges of evaluating an intervention to increase youths’ participation and experiences of social inclusion in the PE context using a multi-method approach integrating quantitative and qualitative approaches. The multi-method approach allowed
an integration of the findings with regard to the implementation as well as the effect of the intervention. First of all, standardized questionnaires provided a manipulation check of the delivery of the intervention, while qualitative observations and interviews identified the diversity in pupils’ reactions thereto. Secondly, quantitative findings on the effect of the intervention were related to qualitative findings pointing to ambiguities in the pupils’ observed behaviour
and interview responses. Thus, a more complete understanding of the implementation processes and effect of the intervention developed.