Ongoing population trajectories in European cities are diverging. Besides population growth, an increasing number of cities faces decline. In this paper, we explore the overall population development of 278 European cities between 1990 and 2008. The analysis presented in this paper seeks to uncover some of the main population trajectories and their related driving forces on the national and individual city level in Europe. In order to understand the probably diverging and highly interlinked forces making for urban population growth, we group European cities according to their population development patterns within the last two decades. We hypothesise that these growth patterns significantly differ across clusters of cities located in different regions in Europe, but also within countries in so far that cities population development might not necessarily follow a strict national way. To illustrate this divergence, we conduct case studies of the major cities in the UK, an established and in Poland, a new member of the EU. We examine the main drivers of their specific population development which can be important economic, social and political forces at both national and regional level. Looking more closely on the impact of drivers related to the demographic change we show how they differently affect the cities of Poland and the UK. Notably in advanced economies of the industrialised Western European countries demographic changes that stem from the Second Demographic Transition started in the early 1970s, earlier than in countries of Central and Eastern Europe, which have started to display classic signs of demographic changes accelerating during the recent decade. Our results did not show one stringent development path of European cities at present. Rather, a combination of different patterns contributes to a specific development of a city which must not be similar to others in the same country. We found that recent population trends not only reflect contemporary socioeconomic adjustments but supranational path dependencies such as demographic change or the transition to market economy. Although Polish cities have rapidly started to experience processes of the SDT since the early 1990s which are similar to those having affected the UK more than 30 years ago, there is evidence that these trends are differently represented in the cities of both countries.