Several aspects of the gap between Italy's Mezzogiorno and its central and northern regions since 1861 are reviewed. At Italy's Unification, Southern Italy showed signs of economic inferiority in comparison with the country's more advanced regions; however, the Mezzogiorno's more advanced areas stood ahead of major areas in Central Italy. Industrialization in the three main regions in the north widened the gap impressively. After the Second World War, a process of convergence took place until the mid 1970s, when the gap stabilized; although no economic catching up has taken place until now, a substantial and impressive convergence is being shown in important well-being indexes. Southern Italy is characterized by a long-term, structural redundancy of labour. In spite of this, the evidence does not allow us to state that public intervention for the Mezzogiorno's development has failed.