The analyses and interpretations that the social sciences have been making in recent decades on the theme of common property call for a fresh look at the history of the commons. Such a vision no longer considers them as resources necessarily destined to disappear, but rather attempts to discover what forces have acted on their historical trajectory. From this perspective, this paper analyses the evolution of common lands in Spain over the nineteenth and twentieth centuries. To that end, it rests on an interpretative proposal that, over time, common lands in Spain have experienced an alteration in their economic usefulness and have had to transform themselves in order to adapt to changing situations. In this context, the various agricultural and, indeed, general economic conjunctures, the evolution of social forces, as well as the make-up of the political system, have all played a major part in the greater or lesser persistence of the commons, in their forms of use and in their more or less successful adaptation to new situations.