In this chapter we present information collected from the population of mule deer in Mapimi, the first Biosphere Reserve in Mexico and Latin America. The reserve was decreed in 1979, covers 342,388 ha and is located at the junction of the states of Durango, Coahuila, and Chihuahua. Mule deer population dynamics data from 14 nonconsecutive years were used to analyze population density, using indirect methods such as counting fecal pellet groups, population structure by age and sex, population growth rate, and their relationship to precipitation in this arid environment. Feeding habits are presented, with mention of the main species in their diet as well as the nutrient content of the latter, diet quality was estimated by sex and age as a function of fecal nitrogen to determine if there were any differences and the relationship of habitat use and diet to sexual segregation. Data on home range and core area size are presented, as are the way in which habitat in the Chihuahuan Desert is being used by the mule deer taking the dry and rainy seasons into account, and how the risk of predation affects behavior using radiotelemetry techniques. Extensive cattle pasturing is the main economic activity in this arid zone and our data indicate that there is little overlap of habitat and little zoonosis, which is a rare occurrence between deer and cattle. The information compiled demonstrates that the population of mule deer in Mapimi is the best studied population in Mexico and should be used as a model to develop suitable strategies to improve the sustainable use of this species. The results also highlight the importance of protected areas as sources of knowledge creation and transfer.