Based on a transdisciplinary perspective, this contribution aims to describe the methodological issues presenting themselves when walking is deployed as a tool to co-produce knowledge in a research project conducted with children. An analysis of two projects, one in Switzerland and the other in Spain, shows the relevance of working across a number of disciplines to study the movement of children and adolescents in their living environment. These research projects use a participatory methodological device, combining the interview and walking technique (mobile interview or accompanied itineraries) as a method of analysing and understanding the experiences of young social actors by prioritising their viewpoints. We also show how adopting a transdisciplinary approach to data co-production enables the participants to inhabit the research through their physical presence and their words.