﻿AbstractThe isopod crustaceans reported from or expected to occur in littoral and sublittoral marine habitats of the Southern California Bight (SCB) in the northeastern Pacific Ocean are reviewed. A total of 190 species, representing 105 genera in 42 families and six suborders are covered. Approximately 84% of these isopods represent described species with the remaining 16% comprising well-documented “provisional” but undescribed species.CymothoidaandAsellotaare the most diverse of the six suborders, accounting for ca. 36% and 29% of the species, respectively.ValviferaandSphaeromatideaare the next most speciose suborders with between 13–15% of the species each, while the suborderLimnorioidearepresents fewer than 2% of theSCBisopod fauna. Finally, the mostly terrestrial suborderOniscideaaccounts for ca. 5% of the species treated herein, each which occurs at or above the high tide mark in intertidal habitats. A key to the suborders and superfamilies is presented followed by nine keys to theSCBspecies within each of the resultant groups. Figures are provided for most species. Bathymetric range, geographic distribution, type locality, habitat, body size, and a comprehensive list of references are included for most species.