Young children's participation has been specifically foregrounded as a pedagogical element within education policy in Wales. However, there is currently little evidence that this policy concerned with participation has been enacted. This research describes an intervention, Spatially Democratic Pedagogy, as a pedagogical approach to foster young children's participation, through design and co-creation of their classroom space. A group of six children, aged 4-5 years, alongside their teacher, were supported through a design-based intervention to enact, document and analyse this process. The research draws upon social understandings of space, as well as Froebel's ideas about construction of communal gardens. Findings illustrate notable differences in the roles and relationships that formed between the teacher and the children when using Spatially Democratic Pedagogy. Children were teachers, planners, architects, negotiators and problem-solvers, as they participated in co-construction of their space. The argument is made that it is the process of design and co-creation that becomes the mediator for pedagogical change and acts as the driver for children's participation. The co-construction of space is an important element to support young children's participation in early years classrooms.