The planning of child-friendly urban spaces is a highly relevant interdisciplinary challenge for anyone involved in creating the city of the future, whether from a spatial, pedagogical or social perspective. More than ever, the involvement of children and teens in these processes is regarded as condition to attain a liveable and sustainable urban environment. To recognize these young people as valuable co-researchers and –planners demands an openness that is not always obvious. This publication was developed in the context of a research project by School of Arts and Faculty of Education, Health and Social Work researchers and combines valuable insights with a set of practical tools to facilitate the exercise of children’s citizenship in processes for planning and changing urban spaces.