The Coastal Cactus Wren is a species of high conservation concern in southern California. The goal of this project was to obtain taxonomic resolution of subspecies boundaries between coastal and desert populations of Cactus Wrens. We collected genetic samples from Cactus Wrens at California desert sites and combined this dataset with previously collected samples from coastal populations to resolve the distribution of subspecies and to determine distinct genetic lineages, gene flow, genetic diversity and effective population size of desert populations. Understanding these relationships will assist managers with development and implementation of a conservation and management strategy that could aim to avoid state or federal listing of this declining species.