Maximum length almost 1 metre. The back is usually brown or grey, but may be green or nearly black. It normally bears a number of dark spots, but these may not be conspicuous. This is an important species in the U.S.A. Its range is from South Carolina to Maine. Further south it is replaced by Paralichthys lethostigma Jordan and Gilbert, the southern flounder.
The name summer flounder was bestowed because the species comes inshore during the summer and in most areas retreats to deeper and warmer waters for the winter.