The distribution of the Cactus Wren (Campylorhynchus brunneicapillus) in northwestern Baja California is something of an enigma. Although widely distributed over most of the peninsula, the species is absent from many areas of seemingly suitable habitat in cactus-filled maritime succulent scrub. Immediately north of the border along the coast, Cactus Wrens were historically widespread, though they are now declining rapidly as increasingly frequent fire and continuing urbanization constrict available habitat. Here, we summarize published and unpublished information on Cactus Wrens in northwestern Baja California, including the recent rediscovery of what may be the region’s only large population of the declining San Diego Cactus Wren (C. b. sandiegensis).