Cities and urban agglomerations are a great phenomenon of the past, present and future. There are tons of materials, studies, books and articles related with cities in terms of urban economics and development (inter alia Capello & Nijkamp, 2004, McCann, 2001, O’Sullivan, 2003 etc.) and agglomeration economics (for more information see for example Glaeser, 2010). We will focus on those that fit to our purpose, in particular to smart cities. The concept of smart cities is currently a very popular and fashionable approach to urban development. Nowadays, almost all cities claim to be more or less smart. Their focus seems to be on the role of Information and Communication Technology (ICT) infrastructure, although much research has also been carried out on the role of human capital, social and relational capital and environmental interest as important drivers of urban growth (Caragliu, Del Bo, & Nijkamp, 2014; Hollands, 2008). The development of a smart city approach and its implementation in various countries has generated impressive research results and policy challenges. Transforming a city into a smart city requires substantial effort from its political representatives, administrators, inhabitants, entrepreneurs, as well as from its various communities. Smart city concept is rapidly gaining momentum and worldwide attention as a promising response to the challenge of urban sustainability in both large and small towns (Bibri & Krogstie, 2017; Caragliu, Del Bo, & Nijkamp, 2011). The size of a city is considered as an important driver of economic development. Empirical evidence from the US and the UK shows that large cities lead to greater productivity and economic growth through the generation of agglomeration economies which allow for a more productive use of available resources (Frick & Rodríguez-Pose, 2017; Melo, Graham, & Noland, 2009; Rosenthal & Strange, 2004). At the same time, many researchers and policy makers have voiced concerns about negative consequences of high level of urbanization on social (i.e. increased urban congestion), environmental (i.e. increased pollution) and economic (i.e. rising interpersonal and interspatial inequality) performance of large cities (Frick & Rodríguez-Pose, 2016). Large cities tend to be associated with diversity and a high concentration of the creative classes. Florida (2005) claims that more densely populated cities with high concentration of creative class are noted for their innovative spirit. In contrast, small and medium sized cities tend to be thought of as places with a healthier environment and a higher ecological awareness. Despite the enormous interest in the area of smart cities, it is not clear from research neither from the practice the impact of a city’s size on the “smartness” of the city. Besides ʻEuropean Smart Cityʼ approach, theoretical and empirical studies on smart cities are overlooking the city size dimension. Therefore, this paper focuses on identifying indicators that allow us to correctly predict the size and the character of European smart cities. The remainder of the paper is structured as follows: the next section describes the theoretical and empirical literature that explores the link between smart cities and size of the city. Main components of smart cities, namely human factor and ICT in the role of crucial components of modern urban development, are discussed in relation to city size. The third section addresses our methodology; used indicators and presents the dataset. The results are included in the fourth section and discussed in the section five. The final part concludes main findings and proposes areas for further research and highlights policy challenges.