This dissertation provides a comprehensive picture of urban shrinkage and its relevance within contemporary urbanization processes in Europe. The thesis demonstrates that shrinking cities are neither a one-dimensional phenomenon nor a side-effect of growth but a unique path of urban development. Thereby, the dissertation address a complex topic that intersects urban geography, demography, planning and spatial modelling thus underlying the interdisciplinary character of this work. Urban shrinkage is an expression of uneven development, particularly visible in the highly urbanized continent of Europe essentially depending on spatial, dynamic, and causal characteristics (Turok and Mykhnenko 2007). Shrinking cities are, first, differently distributed over the continent. Second, their number differ significantly over different time periods. Third, the remarkable expression of urban shrinkage in Europe is rooted in the interplay of various drivers, ranging from economic transformation and suburbanization to changing demographic conditions and political turns. Several studies have provided an idea of the persistence and spatial extent of urban shrinkage and the discussion about how to deal with urban shrinkage had just re-emerged with effects of the global economic crisis. Since 2010, causes, effects, and planning strategies for shrinking cities had been increasingly discussed in an international context. However, a comprehensive picture of urban shrinkage as a multidimensional process in a comparative cross-country perspective feeding this debate, is lacking to a large extent. Concepts and definitions are difficult to apply in empirical research undermining the test of theories. This methodological-conceptual research gap is, first, related to the variations of spatial scales depending on the phenomena under investigation. Second, hitherto studies basically conclude on larger cities although Europe is dominated by small cities. This is, third, related to the provision and comparability of local socio-economic data. Against this background, this dissertation will identify the specific role of shrinking cities within the uneven urban development in Europe. Thereby, theoretical approaches are linked to methodological-conceptual solutions, giving greater credence to the subcomponents of drivers, implications, and spatial variations. The analysis provides solutions to major methodological challenges using spatial statistics and GIS modelling to explore the nature and complexity of urban shrinkage in Europe. Three delineations of cities have been developed allowing a harmonized and flexible application in a cross-country perspective. By linking a unique local population database with other databases three models could have been tested in order to identify variations and specifications of these models related to urban shrinkage. Structured by three research questions, three papers analyse European cities, and two refer to a national and a local case, in order to deepen the results. 1. The assumption, that urban shrinkage represents a broader trend in Europe between 1990 and 2010 can be confirmed. A typology of population trajectories underlines that 49 % of all analysed 7 742 cities in 33 countries can be regarded as one type of shrinking cities. Of these, 14 % show continuous population losses and 23 % episodically losses esp. between 1995 and 2005. Moreover, among the 2 396 temporarily shrinking cities (63 %), 883 cities were affected by recent population losses from 2005 on and 337 ones ceased to shrink. Especially in post-socialist countries a combination of demographic change and fast deindustrialisation drives long-term shrinkage whereas structural economic disadvantages and a constant job-driven outmigration since the 1970s are keeping cities in Northern France or Southern Italy shrinking. In less dense regions of Spain, Western Germany or Austria outmigration of young jobseekers and low attractiveness for families give full rise to the impact of natural decline with fast declining birth rates. Moreover, an increasing mobility of well-educated and trained labour force and the increasing competition between cities accelerates in recent urban shrinkage even in economically advanced regions what indicates that shrinkage is less associated with economic performance due to an increasing gap between productivity and demographics. 2. If shrinking cities are decentralizing or centralizing depends on their spatial distribution. By considering the hinterland, decentralization is driving growing cities towards a hollowing out and aging of the core city especially in Northern France or Poland. In most parts of Europe, urban shrinkage is especially pronounced when the corresponding hinterland declines. By measuring the intensity of the observed core-hinterland processes it is obvious that the general trend of shrinking cities reveal a slowing down of decentralization in favour of centralized decline; in other words: population decline in the cores slowed down and the hinterland lost population faster. The slowing down of core losses is basically due to the immigration of elderly people and a constant weakening of the hinterland accelerating in strong aging. 3. By investigating the complex setting of changes of population and residential area some specifications in terms of density changes in shrinking cities are obvious. Whereas the majority of shrinking cities deconcentrate with land consumption while population declines, almost 9 % of all cities showed a physical adaptation in terms of demolition after 2000. In Romania or the Baltic States densities are further declining because population loss is faster than the physical infrastructure can be adapted. In contrast, large-scale demolition programs lead to the paradox of increasing densities in shrinking cities particularly in Germany. As the example of Leipzig shows, this physical adaptation helped to stabilize the housing market and led to regrowth along with densification. However, density is increasing without an expanding residential area as refurbished buildings are reused. After 2000 this phenomenon covers 10 % of all, predominantly large, cities such as in Germany, the UK and even in post-socialist European countries. Thereby, a twofold polarisation is evident: Whereas the number of growing densifying cities below 100 000 inhabitants decreased, its number among larger ones substantially increased. Moreover, the differences between growing and shrinking small cities increased as an effect of specific spatial relations and drivers. By answering these three questions the dissertation provides a comprehensive picture of shrinking cities in Europe relevant for planning and policy in order to balance the uneven development. By combining socio-demographic, ecological, monitoring and planning aspects the results support a deeper understanding of the multidimensional patterns of urban shrinkage relevant for different levels from local to supranational. In particular, the EU Cohesion Policy may use the results to draw their policy focus from economic related issues to a broader problem-oriented understanding of urban shrinkage (EP 2008). The results serve as basis for further research which extends the database, applies adapted models to other scales or performs different classification methods. The chosen cross-national perspective allows a harmonized comparison of urban trends between countries, reveal the tremendous local variations of uneven development and helps to increase the attention of urban shrinkage within national and supranational debates.