The concept of urban network implies a certain degree of interdependency among cities that are connected by various linkages at different spatial scales. Geographers, but also many other scientists, have theorized the urban network, leading to a wide diversity of definitions and empirical studies. This entry reviews existing approaches through three successive steps: schools of thought across scientific disciplines; operational urban networks in relation to spatial planning; and empirical analyses of intercity transport and other systems. The scarcity of studies offering a multilayered approach to urban networks and/or integrating local socioeconomic determinants motivates further research in this field.