The now voluminous interdisciplinary literature on children’s mobility in cities (environmental psychology, urban design, geography, etc.) has pointed out the decrease of their independance. It has also stressed on the effects on children’s development (social and cognitive) as well as the effects on their health and the quality of urban life.For a few years, in order to avoid the systematic parental car-escorting to school, more and more municipalities are encouraging parental organization to promote “walking to school” with children. And some are supporting new social initiatives of mobility such as the Pedibus. It is a group of children (n=10) who are walking to school escorted by two or three parents educating and safeguarding children against dangers. The implication in Pedibus for children as well for parents enrolling as escorts is more and less durable. It can be used according to contrasting objectives (practical, economical, educative, social...). The spatial (urban design) and temporal (schedules of passages) organization of this trip may have consequences on children’s independent mobility process. It may promote children’s mobility as well as outdoors activities in the city when it is considered by parents as a “springboard” for autonomy. Conversely, it may restrict children’s autonomy if Pedibus is used by parents as a mean only to control their outdoor activities. It depends on how parent and children represent the space of action and competences of children.Within an ecological approach of developmental psychology, we consider children and parents in their daily context with the aim of contributing to a greater understanding of this new emerging initiative of mobility, designated here as an “eco-mobility” (sustainable mobility).Two groups of family were interviewed in Rennes (France) where Pedibus have been experimented for the first time in 2004, in several primary-school of the city-center: children and parents involved in Pedibus versus children and their parents organizing by themselves. Children (at school) and parents (at home) completed a questionnaire about the organization of the whole travels in the city, their motivations to engage in the Pedibus and their representation of the space of action.The results based on comparisons (parents vs. children; family engaged in Pedibus vs. family organizing children’s mobility by themselves) will allow us to describe who are the families engaged in Pedibus, why do they choose this form of mobility and for how long. Results will also indicate the effects of the Pedibus experience on children’s mobility process.