The article begins by showing that the traditional concept of industrial sector has been radically criticized on both theoretical and empirical grounds. The reasons for the concept's inadequacy are raised, and they are identified as: (i) the fact that in a rapidly changing world empirical classifications must be changed; (ii) the fact that when scholars seek to classify reality they must take account of the classifications of that reality made by the actors concerned. Given the diverse importance for different productions of technology and social context, of tacit and codified knowledge, the article sets out some practical rules, exemplified by the Italian footwear industry, for empirical research. It then proposes to dynamize analysis of the Marshallian industrial district, first conceptually in its elementary processes, and then with a view to empirical study of the convergence of these processes on the district form and the reasons for reviving the district analysis originally formulated in the 1960s a...