The pictographic sequence in the Lower Pecos River region of Texas illustrates the contribution that rock art can make to the reconstruction of prehistoric cultural systems. The indigenous development and later introduction of mature art forms contrast markedly with the current static model of hunting and gathering adaptation to this now-arid region. Four prehistoric rock art styles and the historical pictographs are described in chronological order and in the context of archeological remains. The difference between the perceptions of prehistoric lifeways afforded by studies of art forms and those that concentrate on material culture are attributed to the degree of constraint exerted on each subsystem by physical factors. Environmental conditions, such as the limited availability of water, the desert biotic community, and the geologic distribution of rock shelters, place limits on the strategies of subsistence, technology, and settlement, the data classes most important in ecological models. Behavioral subsystems, such as those manifested in the rock art, are more pliant, reflecting social and ideological influences that are more difficult to detect in the analysis of material culture.