Urban and spatial planning developed as a new discipline on a European level at the beginning of the 20th century. The first planning course was established in Liverpool (UK) in 1909. The first planning course in Germany was founded at TU Dortmund University in 1969. With a view to the historical context, the question arises as to the social framework conditions and catalysts in which the new planning discipline developed. In order to analyze this in more detail, the proposed research project pursues a cross-epochal, internationally oriented and interdisciplinary comparative approach. By focusing on several key epochs, which will be analyzed with a different focus and repertoire of methods, but with a common interest in knowledge, a systematic contribution will be made to the constitution of spatial planning as a function of social conditions. The research project will reflect on the existing historiography of the discipline with its assumed milestones in the development of the discipline, and new insights are expected into the background to the re-founding and establishment of spatial planning as a discipline.