This project will develop a computer-based identification system for plants and animals. The system, named Symbiota, will introduce an improved data model and highly efficient computer programs to speed the identification process. Based on hierarchically organized data linking descriptions of characteristics to taxonomic ranks this system dynamically builds identification keys for any user determined combination of species of interest. The implementation of inheritance and object-oriented principles in Symbiota greatly reduces data entry efforts, handles species concepts for vastly different taxonomic groups in one system and accommodates varying phylogenic or taxonomic views. The system determines the applicability of characters to the species in question at every step of the identification process dynamically adding the more specific characters and removing the more general ones as the choice of possible species is being narrowed. Although the system may be used independently, in this project Symbiota will be integrated into the Southwest Environmental Information Network (SEINet: http://swbiodiversity.org/seinet/index.php), a mature biodiversity information center for the southwestern US and northern Mexico.The SEINet collection records provide a wealth of locality information as well as specific taxonomic information that can be used to generate user selected lists of species such as a list of all conifer species within a state park. These lists can be used with Symbiota to dynamically construct an identification key to those species excluding plant species not in the park as well as including only the characteristics for plants which actually appear in the park. Therefore, the system has the enormous potential to be as comprehensive as the professional taxonomist expects it to be or as simple as a primary school student needs it to be when being introduced to the plant species on the school grounds.