Using a socio-material approach to analyze knowledge production in municipal planning offices in Lisbon, Vienna, Vancouver and Zurich and borrowing from Science and Technology Studies, this paper suggests to apply a relational perspective on planning. It is based on the idea of an analytical symmetry between heterogeneous entities, such as human and non-human actors. Cases, such a rezoning controversy in Vancouver, public engagement initiatives in Vienna and Zurich as well as urban development projects in Lisbon, Vienna and Zurich, are used to shed light on the multifaceted relations between which planning knowledge is produced and how competing claims in planning are developed, debated, and settled. Such a socio-material analysis focuses on the ways, planning knowledge, planning practice and public knowledge are related to each other. Furthermore, the formal organization of the urban planning offices, the processes and procedures as well as the disciplinary backgrounds of the planners have an impact on their framing of the planning object; the city and space, the planning process, public participation as well as on how the planners design their projects. As a consequence, planning outcomes can be seen as a reflection of such relations.