Our aim in this article is to lay some statistical and theoretical foundations for an understanding of Italian post-war economic growth, by devoting special attention to what has happened in the hundred different “Italies” that go to make up the mosaic of this country. We have concentrated our analysis on comparing “areas of large enterprise” with “industrial districts” through a distinction between district provinces (IDPs), large enterprise provinces (LEPs) and other provinces (OPs). We investigate manufacturing industry by means of in depth analyses of trends in employment and value added, as well as through breakdowns of export flows and income and prosperity levels. Since the end of World War II it appears that Italian economic growth has largely been formed by the constant, massive flow of exports of personal and household goods and light mechanically-engineered products, that a sizeable flow of exports is attributable to growth in the industrial districts, and that although the income gap between the different parts of the country has not been eliminated, growth by the industrial districts and the policy of industrialization in Southern Italy have together engineered a major territorial dispersion of both light and heavy industry. However, heavy industry and high-tech large Italian companies have found increasing difficulties and even lost many of the positions they once held. Our survey indicates that a policy for industrial development in Italy must take account of the weakness of the heavy industry sector along with the features and requirements of industrial districts.