The diets and foraging patterns of four sympatric rodents (Eutamias minimus, Thomomys talpoides, Peromyscus maniculatus, and Microtus montanus) were studied for three summers in subalpine meadows in northern Colorado. The rodents were taken in half-acre quadrats isolated by electric fences, and the diets were determined by microscopic examinations of stomach contents. Records of times of capture and frequency data on the plants at capture sites contributed to an evaluation of feeding biology. Each species utilized a different feeding strategy; the species with broadly similar diets had contrasting specific food-item preferences and were spatially or temporally separated during foraging. Thomomys talpoides and M. montanus were both entirely herbivorous, but each preferred different plants and different size classes of plants, and they foraged in different microenvironments. Both E. minimus and P. maniculatus ate primarily seeds and arthropods, but they preferred different kinds of seeds and depended on arthropods to differing degrees; E. minimus was diurnal and P. maniculatus was nocturnal. Feeding niche displacement between the rodents was especially striking during spring snowmelt and after late summer frosts, times when food was in short supply. The striking changes in the diets of the rodents during the summer and relationships between diets and feeding-activity rhythms are discussed.