Emydidae (Latin emys (freshwater tortoise) + Ancient Greek εἶδος (eîdos, “appearance, resemblance”)) is a family of testudines (turtles) that includes close to 50 species in 10 genera.

The upper shell (carapace) of most emydids is the shape of a low arch, although in some species, it is domed.

The upper shell may have one or two ridges that run from front to the back of the animal (a projection commonly called a "keel"), or such a feature may be absent.

Emydids have large bottom shells, and some members of the family have a movable hinge that separates pectoral and abdominal segments (scutes).

Knowledge of reproductive behavior ranges from some of the most detailed, long-term study of any taxon (Chrysemys picta in Michigan) to a total lack of information.

The pond slider (Trachemys scripta) has expanded its range through the careless release of pets into the wild.

The enigmatic big-headed turtle (Platysternon megacephalum) was for some time considered a specialized, but still very primitive early offshoot of the Emydidae.

Many other extinct species traditionally placed in the Emydidae are known from the Eocene of North America, Asia, and Europe, but the Old World taxa are likely to be more properly Geoemydidae.