The issue of urban shrinkage has become the new ‘normal’ across Europe: a large number of urban areas find themselves amongst the cities losing population. According to recent studies, almost 42 per cent of all large European cities are currently shrinking. In eastern Europe, shrinking cities have formed the overwhelming majority – here, three out of four cities report a decrease in population. Shrinkage has proved to be a very diverse and complex phenomenon. In our understanding, a considerable and constant loss of population by an urban area classifies it as a shrinking city. So, while the indicator of shrinkage used here is rather simple, the nature of the process and its causes and consequences for the affected urban areas are multifaceted and need to be explained and understood in further detail. Set against this background, the article presents, first, urban shrinkage as both spatially and temporally uneven. Second, this article shows that the causes of urban shrinkage are as varied as they are numerous. We explore the ‘pluralist world of urban shrinkage’ in the European Union and beyond. The article provides an original process model of urban shrinkage, bringing together its causes, impacts and dynamics, and setting them in the context of locally based urban trajectories. The main argument of this arrticle is that there is no ‘grand explanatory heuristics’ of shrinkage; a ‘one-size-fits-all’ explanatory approach to shrinkage cannot deliver. To progress and remain relevant, one ought to move away from outcome-orientated towards process-orientated research on urban shrinkage.