The aim of this chapter is to assess the degree of connectivity and centrality in global networks of the main Spanish Functional Urban Areas. These include the two main first-tier global cities (Madrid and Barcelona), as well as other second- and third-tier cities that function as regional capitals. The hypothesis is that the economic performance of these cities is linked to their position in global networks that provide access to information, business opportunities and external resources. This is particularly relevant for second- and third-tier cities, which can benefit from “borrowing size” from larger centres or, more generally, from the network. Agglomeration economies would then be complemented by network economies, improving social and economic development prospects. To operationalise the study, we will configure the urban network using origin-destination matrices of academic staff mobility actions within the European Erasmus+ programme. A diachronic perspective will be adopted to identify the main trends in the Spanish urban system between 2015 and 2022, which will be related to basic economic performance variables. The results support the idea that the benefits of participation in global networks are no longer limited to first-tier cities, but have gradually reached lower levels of the national urban system.