The genus Capnia in North America is reviewed and compared to other genera in the family. The genus is divided into 10 species groups. A key to the 51 species of Capnia in North America is given along with a listing of type localities, type repositories, diagnoses, and distributions. New illustrations of structures bearing characters important for identification and classification are presented. An annotation of the list of Capnia of North America given by Stark, Szczytko, and Baumann (1986) reflecting current generic placement of species is produced. From this list Capnia bakeri and sugluka are moved to Mesocapnia. Capnia barbata Frison is placed in synonymy under Capnia decepta. The movement of cygna (synonym of venosa), elevata, fibula, manitoba, venosa, and wanica to Capnura (Nelson and Baumann, 1987b) is noted. Capnia disala and ensicala are placed in Paracapnia.