Abstract: This study examines plant and small mammal communities along elevational gradients in the Mojave Desert as well as characteristics of disjunct montane pinyon-juniper woodlands and the rodents that inhabit them. After a brief introductory chapter, Chapter 2 provides a depiction of the vegetation of the Mojave Desert and how it changes with elevation along six different mountain ranges. Elevational patterns in plant species diversity, density, cover, and volume are described and the current distribution of plant communities and their individual characteristics are documented. Chapter 3 examines the abundance and distribution of small mammals at both the regional and species level along six elevational transects. This information is combined with plant data from the same transects to interpret variation in small mammal species richness and distribution. Patterns of small mammal species diversity along the elevational gradient are also examined. Chapter 4 provides a general description of four pinyon juniper woodland fragments in the Mojave Desert and the rodent communities that inhabit them. Elevation plays an important role in the distribution of plant and small mammal communities in the Mojave Desert. The elevation of maximum small mammal species richness coincides with the location of habitat transition between desert scrub and montane vegetation types. Explanations for variation in elevation of the lower boundary of pinyon-juniper woodland among the mountain ranges are discussed. The abundance and distribution of small mammal species along the elevation gradient indicate that taxonomically, morphologically, and ecologically similar species occupy different plant communities or areas with different habitat characteristics. For both plants and mammals and regardless of distance, sites within contiguous pinyon-juniper woodland habitat are more similar than sites in different habitat fragments. The vegetation structure of pinyon-juniper woodlands varies among mountain ranges as do the small mammal communities. In particular, the woodland in the Panamint Mountains has a very dense population of Pinus monophylla which causes a low density and diversity of shrubs and in turn, a low diversity of rodent species.