Nesting occurs from late May to mid-July. The female prepares a flask-shaped nest in slightly moist loamy or sandy soil at a sunny site near water. The number of eggs laid varies from 2 to 20, differing among the subspecies. Incubation in nature and in captivity averages 76 days. The influence of incubation temperature on hatchling gender is well-documented in painted turtles.
Hatchlings emerge from the egg with the help of the caruncle or eggtooth.
The caruncle drops off a few days after hatching. The hatchlings have a keeled shell and an abdominal fold, both of which disappear as they grow. Their shell pigmentation and markings are brighter and more pronounced than those of adults. They mature about five years after hatching and are thought to live as long as 20 years. Wild hatchlings may overwinter in the nest.