Five-lined skinks were studied for four consecutive years in four small areas, totalling approximately ten acres, on the University of Kansas Natural History Reservation, Douglas County, Kansas. The information gained from intensive study on these areas has been supplemented by data from skinks collected elsewhere in northeastern Kansas, and from an extensive literature pertaining to this species. The genus _Eumeces_, to which the common five-lined skink belongs, has more than 50 species, occurring throughout Central America, North America to the latitude of southern Canada, and, in the Old World, across southern Asia and North Africa. Within the genus, the five-lined skinks, comprising a dozen species, form a natural group of closely related forms. In this "_fasciatus_ group" nine of the species occur in the Orient, Japan and neighboring islands and the adjacent mainland. The remaining three, including _E. fasciatus_, occur in the eastern United States. Specific differences are to be found in details of pattern, scalation, and size, and, in some instances, they were long unrecognized. _E. fasciatus_ coincides closely in its distribution with the Deciduous Forest Biome of southeastern North America. An early Tertiary deciduous forest in Alaska and probably in the Bering Strait area, evidently growing in a humid, mild-temperate climate, included genera of plants that are now most characteristic of southeastern North America along with other kinds now characteristic of forest remnants in southeastern Asia, and still others characteristic of the western United States. The _fasciatus_ group seemingly dispersed from a northern center that may have coincided with the early Tertiary deciduous forest of Alaska. _Eumeces laticeps_ almost coincides in distribution with _E. fasciatus_, but does not occur quite so far north, and unlike _fasciatus_ it occurs throughout Florida. Young are similar in appearance but _laticeps_ is a larger, more powerful species, notably arboreal in its habits. _E. inexpectatus_ much more closely resembles _fasciatus_, and ecological divergence is slight. It is characteristic of hot and dry rocky areas in open woods, and is more southern in distribution, although there is extensive overlap with _fasciatus_ and _inexpectatus_ shares nearly all of its range with _laticeps_.