The Common Wood-nymph can vary greatly. All individuals are brown with two fore wing eyespots, the lower one often being larger than the upper one. Some may have many, few, or no eyespots on the ventral surface of the hind wing. In the southeastern part of its range, it has a large yellow patch on both surfaces of the fore wing. In the western part of its range, it may have a pale yellow patch or may be lacking one. Individuals in the northeastern also lack the yellow patch, i.e., C. p. nephele. In individuals with no yellow patch, there are two pale yellow eye rings that encircle both the fore wing eyespots. The wingspan measures 5.3 to 7.3 cm (2.1 to 2.9 in).
The Common Wood-nymph is found in a variety of open habitats, such as open woodlands, woodland edges, fields, pastures, wet meadows, prairies, salt marshes, and savannas
The female Common Wood-nymph is the active flight partner. The female lays her eggs on or near the host plant. The egg is pale yellow, later turning to a tan color with orange or pink blotches. The caterpillar makes no shelters or nests. It is green or yellowish-green with darker green stripes that run the length of the body. It has two short pinkish projections on the end of the abdomen. It has yellow spiracles and is covered in thin, white hairs. The caterpillar will reach a length of 5 cm (2 in). The Common Wood-nymph caterpillar is very similar to satyr caterpillars in the genera Hermeuptychia, Cyllopsis, and Neonympha. It can be separateed by its larger size and habitat. The pale green chrysalis is striped in white or pale yellow. The first instar caterpillar hibernates.