This paper reports on the first two decades of research on smart cities by conducting a bibliometric analysis of the literature published between 1992 and 2012. The analysis shows that smart-city research is fragmented and lacks cohesion, and its growth follows two main development paths. The first one is based on the peer-reviewed publications produced by European universities, which support a holistic perspective on smart cities. The second path, instead, stands on the gray literature produced by the American business community and relates to a techno-centric understanding of the subject. Divided along such paths, the future development of this new and promising field of research risks being undermined. For while the bibliometric analysis indicates that smart cities are emerging as a fast-growing topic of scientific enquiry, much of the knowledge that is generated about them is singularly technological in nature. In that sense, lacking the social intelligence, cultural artifacts, and environmental attributes, which are needed for the ICT-related urban innovation that such research champions.

The application of practice theories in the domain of sustainability research in consumer studies is increasingly advocated based on the premise that this allows to analyse consumption as a social phenomenon. Consequently, the applications of social practice theories to this field are expanding geometrically and to date, little retrospective work on this evolution has been made. We conduct a bibliometric analysis of applications of practice theories in the domain of sustainability research in consumer studies. Our results show a temporal succession of research trends: ‘consumer identity’ dominated the field between 2009 and 2012, ‘business and governance’ between 2012 and 2014, ‘sustainable consumption and production’ between 2013 and 2014, ‘urban living and policy’ between 2014 and 2015 and ‘household energy’ from 2015 until the present. We see a high potential of future applications of practice theories in the fields of the sharing and circular economy, as well as in research on smart cities. We provide new insights into the evolution and future trends of applications of social practice theory to domains that are relevant for research on sustainability and consumer studies.

This Special Issue begins with a middle-range theory of sustainable smart city transitions, which forms bridges between theorizing in smart city development studies and some of the foundational assumptions underpinning transition management and system innovation research, human geography, spatial planning, and critical urban scholarship. This interdisciplinary theoretical formulation details our evidence-based interpretation of how smart city transitions should be conceptualized and enacted in order to overcome the oversimplification fallacy resulting from corporate discourses on smart urbanism. By offering a broad and realistic understanding of smart city transitions, the proposed theory combines different smart-city-related concepts in a model which attempts to expose what causal mechanisms surface in sustainable smart city transitions and to guide empirical inquiry in smart city research. Together with all the authors contributing to this Special Issue, our objective is to give smart city research more robust scientific foundations and to generate theoretical propositions upon which subsequent large-scale empirical testing can be conducted. With the proposed middle-range theory, different empirical settings can be investigated by using the same analytical elements, facilitating the cross-case analysis and synthesis of the systematic research efforts which are progressively contributing to shedding light on the assemblage of sustainable smart city transitions.