In this article, the authors examine how materiality can be understood as a co-creator and significant carrier of social processes. They focus on the ways children in large sibling groups relate to bedrooms and identify the logics at play when the organizing of children’s bedrooms and siblings are interwoven. Children have dreams and expectations of establishing a space by way of having their own room and stuff, and they implement this desire for ownership through specific strategies to obtain material presence and leave territorial marks, which afford them positioning and recognition within sibling relations and families. The authors’ analysis clearly shows that children gain material weight across households with varying material resources and different socio-cultural views on how to allocate these resources. It also shows that processes surrounding the material constitution of siblingships are embedded in a child-focused society with strong cultural norms about what constitutes a good life for children.