This study analyzes genetic population structure in the cactus wren throughout coastal southern California using microsatellite markers developed specifically for this species. It expands upon a previous study focused in Orange and San Diego Counties (Barr et al. 2012), adding cactus wren samples from Ventura, Los Angeles, San Bernardino, and Riverside Counties. Additional samples from Palos Verdes and West Coyote Hills were included in the original dataset in an addendum to the study. With this full dataset, we characterize the current population genetic structure to provide information on levels of gene flow throughout the cactus wren’s range in coastal southern California. We also analyze genetic diversity and recent demographic change over the study area. Understanding these patterns will aid in management of current cactus wren populations and future efforts in habitat restoration.