The fritillary genus Speyeria is represented by 10 species in California and Nevada. All the species are univoltine and their only known food plants are the North American Viola. Most of the species have broad geographic ranges but usually occur colonially within their ranges and are confined to certain elevations and habitats. Some of the species are distinct morphologically while others are virtually indistinguishable in some locations. Most of the species have phenotypically distinct subspecies. Sixteen loci were analyzed electrophoretically for each of the 10 species to determine the genetic differentiation between species and subspecies. Heterozygosities ranged from 0.034-0.149 with a mean for the 10 species of 0.102. The average genetic distance between the species was D̄ = 0.182 ± 0.013. Using these gene loci as diagnostic characters, five of the 10 species were not distinguishable from each other with a probability greater than 0.95. The average genetic distance between subspecies was D̄ = 0.023 ± 0.008. The more vagile species, S. zerene, was found to have less differentiation between its subspecies than S. callippe which is strongly colonial. The average genetic distance between local populations was D̄ = 0.013 ± 0.003. The Lewontin-Krakauer test was used to test for heterogeneity of the estimated effective inbreeding coefficients, F̂e, among populations of S. callippe and S. zerene. When subspecific boundaries were ignored, we found significant heterogeneity in the F̂e values. However, in the one subspecies where we had sufficient data for the test, S. callippe liliana, we found no significant heterogeneity. These results indicate that either selection is an important factor in maintaining protein polymorphisms or that the Lewontin-Krakauer test is quite sensitive to deviations from the assumed population structure.