Reconsidering institutional change: Property rights in northern Spain

For about fifty years, from the turn of the twentieth century until the 195 0s, farmers in the region of the Orbigo River in northwestern Spain lifted groundwater for irrigation. Two quite different forms of property rights em erged during this period. In the Orbigo valley, small groups of farmers hel d the majority of water-lifting devices and groundwater as common property. Water was divided into timeshares and shares were taken in rotation. On a high plain above, farmers held water-lifting devices and groundwater as pri vate property. Why did two different forms of property rights emerge in thi s place at this time? In addressing this question, a new approach to unders tanding institutional change is proposed, based on a synthesis of schema th eory and the economics of institutions.