Over the last three decades knowledge driven governance in the youth field has gained in importance. A conditional prerequisite is that evidence-based policy making emerges from empirical data analysis. This does not happen by magic. The following article starts from an in-depth analysis of a surprising indicator value, concerning young people’s electoral participation in Luxembourg and finally, develops a view on how evidence could ideally be produced. Measuring a concept is obviously not enough; evidence should namely be firmly grounded in a new role of the researcher, a reflective professionalization going beyond traditional confines and embedded organizational structures allowing a fruitful interaction between social research and decision making.