This paper studies the evolution of Spanish regional inequality from 1860 to 2000. The results point to the coexistence of two basic forces behind changes in regional economic inequality: differences in economic structure and labor productivity across regions. In the Spanish case, the initial expansion of industrialization during the period 1860-1900, in a context of growing economic integration of regions, promoted the spatial concentration of manufacturing in certain regions, which also benefited from the greatest advances in terms of labor productivity. Since 1900 and until 1985, the diffusion of manufacturing and services production to a greater number of locations generated the emulation of production structures and a process of catchi...