The methodological challenges in the research on children's subjective understandings of well-being are very close to the ones surrounding the implementation of the right of the child to be heard. Therefore, identification of the factors favouring or impeding children's freely expressed views on the one hand, and preliminary results of research on children's subjective well-being on the other hand, reciprocally inform each other. The right to be heard is approached from the perspective of capabilities (Stoecklin & Bonvin 2014) identifying factors that are converting this formal freedom into real freedom. They highlight preliminary results of a qualitative study conducted in Switzerland along the procotol of the Child's Subjective Well-Being study (Hunner-Kreisel et al. 2016). The inclusion of a participative research tool, the “actor's system” (Stoecklin 2013), has allowed to concentrate on children's subjective understandings of their experience. The results are not analysed in terms of statistical representativeness, but rather in terms of « structural » features they allow to highlight. The endeavour is methodological. The analysis shows that language itself can be a conversion factor in the implementation of the right to be heard, and similarly a methodological trap inducing specific translations of children's voices into the official “vocabulary” of well-being. Research protocols should therefore be adapted to the evolving capacities of children, considering that well-being is not given state but rather a subjective feeling stemming from processual social dynamics in which children play a part, even when they have little voice.