In the summer of 1962 an outdoor enclosure of 100-foot circumference was constructed, of galvanized sheet iron, with wall three feet high, set on a concrete base extending to a depth of two feet. A two-foot-deep concrete basin inside the enclosure served as a water container. The enclosure was partly shaded by a large walnut tree and the area enclosed had lush vegetation, including brome grass, various shrubs, and young trees up to 15 feet high, thus including most features of the racers' habitat, and it was situated in an area frequented by the snakes. Throughout the summer several racers were kept in the enclosure, and frequent observations on them yielded much information concerning time of activity, temperature preferences, and social and sexual behavior that could not have been obtained readily either from racers confined in small cages or from those free under natural conditions. Description _Color Pattern_ Hatchling racers differ much in appearance from adults; whereas the latter are of dull uniform coloration dorsally, the hatchlings have a checkered pattern of alternating blotches in several rows, including a middorsal row, with blotches much larger than those of the other rows. This basic pattern is perhaps the most common one in all snakes, and is found in the young of various other genera (notably _Elaphe_) which lose or alter their markings during development. In these genera and in the racer, the juvenal checkered pattern may represent recapitulation of an ancestral condition. The adaptive significance of having a blotched, checkered pattern in the young, and uniform coloration in the adult is not evident. I have rarely seen the hatchlings under natural conditions except by finding them hiding beneath flat rocks. Their concealing pattern must be fully as effective as that of adults and the young themselves are more secretive than the adults.