Different definitions of planning exist. They have in common that each contains ‘the future’ and ‘space’ in a wider or narrower sense. However, planners are not just architects for greater spaces. Architects draw plans which will be implemented in exactly that way by the investors or landowners. Planners, however, need to convince stakeholders and must rely on their ability to implement their ideas. So, spatial planning cannot be reduced to drawing an urban design plan. Rather spatial planners need to be able to estimate and influence the future activities of many stakeholders. They have to expect the unexpected and prepare the space for it. Planning theory can be used as a tool for expecting the future. The course on planning theory aims at enabling students to plan with the unexpected. The rationale to planning theory in this course is to regard planning theory not as some abstract analysis of planning practice, but rather as a useful tool for planners. In addition, it will be emphasized that there is not one comprehensive planning theory out there, but rather that planning theory is a result of a discursive process. Planning theory always needs planning practice to adjust and reflect on itself in order to improve its viability as a tool.