This report summarizes the results of the first comprehensive inventory of plants and vertebrates at the Tucson Mountain District (TMD) of Saguaro National Park, Arizona. From 2001 to 2003 we surveyed for vascular plants and vertebrates (amphibians, reptiles, birds, and mammals) at the district to document the presence of species within its boundaries. Park staff also carried out extensive infrared-triggered camera work for medium and large mammals from 2002-2005 and results from that effort are reported here. Our spatial sampling design for all taxa employed a combination of random and nonrandom survey sites. Survey effort was greatest for medium and large mammals and herpetofauna. Because we used repeatable study designs and standardized field methods, these inventories can serve as the first step in a biological monitoring program for the district. We also provide an overview of previous survey efforts in the district. We use data from our inventory and other surveys to compile species lists and to assess inventory completeness. The survey effort for herpetofauna, birds, and medium and large mammals was the most comprehensive ever undertaken in the district. We recorded a total of 320 plant and vertebrate species, including 21 species not previously found in the district (Table 1). Based on a review of our inventory and past research at the district, there have been a total of 723 species of plants and vertebrates found there. We believe inventories for most taxonomic groups are nearly complete. Based on our surveys, we believe the native plant and vertebrate community compositions of the district are relatively intact, though some species loss has occurred and threats are increasing, particularly to herpetofauna and larger mammals. Of particular note is the relatively small number of non-native species and their low abundance in the district, which is in contrast to many nearby natural areas. Rapidly expanding development on the west, north, and east sides of the district is cause for concern that the park continue its commitment to environmental restoration, which is largely responsible for reducing the threats posed by non-native plants. With continued maintenance of natural processes and the ecological structure of the park's biodiversity, the park will become an increasingly important place to both the general public and the scientific community. This report supersedes results reported in Powell et al. (2002, 2003).