This study synthesized the results of 38 ichthyofaunal studies from a wide range of habitats within the Southern California Bight. Quantitative clustering of sites based on species composition yielded nine distinct groups designated as bay/estuary (BE), open coast sandy beach (OC), harbor/nearshore soft bottom (H/NSB), nearshore midwater (MW), offshore soft bottom (SB), rocky intertidal (IT), shallow rock reef (SRRF), deep rock reef (RRF), and kelp bed (KB). Clustering of the 105 species produced 19 groups of both widespread and habitat specific species. Calculation of H' and J' diversity indices yielded virtually indistinguishable rankings among habitat types with the SB, KB, and RRF habitats showing highest fish diversity in general and MW, BE, and IT the lowest. Possible explanations for the observed patterns of diversity among the nine major habitats are discussed.