This paper discuss principles for the design of a tool to screen 3- and 5-year-old children's social situation of development in Greenland. We describe this tool as radical-local, building it on a theory of child development that focuses on children's activities as cultural, anchored in local conditions and traditions, where play is seen as the core activity for preschool children. In constructing Investigating children's situation of development (Undersogelse af borns udviklingssituation - UBUS 3 and UBUS 5) we have aimed at creating an instrument that can be used to evaluate children's health, wellbeing and activities in their everyday settings of day-care and at home in Greenland. The assessment focus on interaction with care-persons and other children, not on children's abilities as isolated and independent features. For preschool children these conditions and their participation in these conditions create the child's social situation of development.