Current debates show a rising awareness that several cities in Europe and the US have to deal with challenges of long-term demographic and economic changes leading to urban shrinkage associated with housing vacancies, underused infrastructure and other negative impacts. On an international scale, it is still not clear if or in what way planning paradigms, planning systems, planning strategies, and planning cultures are adapting when faced with urban shrinkage. Bridging both the US and European discussion on planning cultures by means of an evidence-based comparative research work is a new and innovative approach in spatial research.In this context the following two aims and respective research questions will be investigated:1. Identify paradigm shifts, and possible changes in planning systems and planning cultures in view of shrinking cities in Germany and the USA(Which assumptions and values regarding planning have changed or have been adjusted?, What are the options for a shrinking city? )2. Develop a toolset to evaluate planning strategies for shrinking cites(Which requirements for future oriented planning from the international comparison can be utilized for shrinking cities?, What are major benchmarks for the perception of shrinkage, which could be utilized as an early warning system?).The project makes use of an embedded case study approach. This will facilitate in-depth investigations of the stakeholders involved in shrinking cities - their motivations, actions, and the limits they are confronted with. Four case studies will be selected: two cities from Germany, and two cities from the USA. In order to provide the basis of a comparative analysis, two analytical approaches of planning systems will be synthesized: the culturized planning model (Knieling and Othengrafen, 2009), and a typology of planning strategies (Pallagst, 2007).