This text introduces a set of papers representing the main contribution of the "Florence school" to contemporary literature on industrial districts. The authors illustrate that the revitalization of the concept of industrial districts, returning to Alfred Marshall's 19th-century writings, is rooted in an unconventional interpretation of the economic development of Tuscany after World War II. Models of industrial organization and empirical investigation of industrial tendencies are featured, and Alfred Marshall's concepts of the advantages of the geographical agglomeration of specialized small...