The Globalization and World Cities (GaWC) research network was founded at Loughborough University in 1998 by Peter Taylor and Jon Beaverstock as an invitation to urban scholars across the world to help understand the changing worlds of cities under conditions of contemporary globalization. These changes were so dynamic, so unusual and so worldwide that they were beyond the comprehension of any one group of researchers in one place to even begin to adequately research this then-emerging field of study. GaWC’s core business has been to more narrowly focus on one conspicuous topic in research on globalized urbanization: the external connections of world cities. Just as world/global cities research as a whole never intended to provide a comprehensive account of globalized urbanization (Parnreiter 2014; van Meeteren et al. 2016; Harrison and Hoyler 2018), so too the formal analysis of worldwide networks between cities is not necessarily the main activity of world/global cities research. Nonetheless, as the latter literature is premised upon the existence of interactions between cities, these should not be neglected as they so commonly were in earlier global/world city literature (Taylor 2001a); GaWC was thus formed to aid in rectifying this situation. Although world/global city research in general and GaWC in particular is best described as an ‘invisible college’ (Acuto 2011; Bassens and van Meeteren 2015) - that is, a continuously evolving group of authors in a particular research field who constitute a social circle, but have varying degrees of involvement and pursue different research questions on the basis of shared interests - the research ethos of GaWC at large has been critical realist (Sayer 1992). In practice this implies that we firmly believe that these extensive quantitative studies should exist alongside, and be connected to, intensive qualitative investigations of world city-formation (see Watson and Beaverstock 2014). Examples of a fruitful combination of formal quantitative analysis and qualitative research strategies can be found in studies on the connections between London and Frankfurt at the time of the euro currency launch (Beaverstock et al. 2001) and on the connections between New York, Los Angeles and Detroit in light of changing advertising practices (Faulconbridge et al. 2011). Literature that contextualizes, challenges and provides formative interpretations of extensive quantitative studies remains a vibrant strand of research (Watson and Beaverstock 2014), and includes Lai’s (2012) analysis of the Beijing-Shanghai-Hong Kong triad and W-jcik’s (2013) analysis of the commonality, complementarity and connectivity between New York’s and London’s financial markets. In addition, the broader question of the nature of world cities as sites through which economies flourish is also being addressed (Taylor 2013; Bassens and van Meeteren 2015).