Research in planning as a design science Planning is not just concerned with understanding the world, but also, and fundamentally, with changing it. Academic research in planning should reflect this fact, which sets it apart from research in most natural and social sciences. These are primarily concerned with comprehending phenomena, and only secondarily and indirectly with influencing them (if at all). In this respect, research in planning appears closer to research in disciplines such as management, law, engineering, or medicine, which, in spite of great differences in their domains of application, are all primarily concerned with how to affect (rather than just describe and explain) their objects of study. Much academic research in planning does not seem, however, to acknowledge this. In this paper, we will argue why we believe so, and propose an approach to academic research in planning that might better reflect its primary concern with changing, rather than just understanding, planning practices. However, first we need to elaborate further on the notion of an orientation of research towards understanding as opposed to an orientation towards change, and on the implications of the difference. In order to distinguish it from the`explanatory science' type of research that all research tends to be identified and compared with, Van Aken (2004; 2005) calls change-oriented research`design science' [inspired by Simon (1969); see also Scho« n (1983)]. What design sciences have in common is the awareness that``understanding a problem is only halfway to solving it. The second step is to develop and test