Children up to five years of age, who are suffering from cerebral palsy, place great demands on mobility aids. This is especially so when they cannot move themselves forward by way of walking, need support for a sitting posture, cannot use their hands easily and have limited perceptions. They often have a wheelchair to be able to sit for a long time and move around indoors. Outdoors they are transported over greater distances by their parents in a push chair. A project has been set up at the Faculty of Industrial Design Engineering of the Delft University of Technology in order to develop a mobility aid, which creates new opportunities for independent activity and experiences with mobility. This paper deals the result of the first phase of this project: a programme of requirements with respect to the seating device of the mobility aid. The seat should be provided with adjustable elements in order to meet the need for support of each individual child.@en