In spite of considerable fluctuations in the likelihood of agricultural success from place to place and from time to time, the southern Colorado Plateaus show a smooth increase in farming populations between A.D. 1 and 1150. At the local level, however, population curves in this region often register a pattern of short-lived occupations and abandonments that are tied to specific patterns of short-term and long-term climatic conditions. The prehistoric population record from the Dolores area, in the southwestern corner of Colorado, demonstrates how localized population adjustments to climatically sensitive environments can result in long-term population increases. Here, a 600-year history of population increase was maintained primarily through population movements between environmentally complementary places. When that strategy failed, due to a combination of adverse short-term and long-term climatic conditions, agricultural methods shifted from rainfall farming to intensified agriculture supported by water-control facilities.