Fifty-one species or species complexes of black flies are recorded from Alberta representing the following genera: Cnephia Enderlein (1), Ectemnia Enderlein (2), Gymnopais Stone (1), Mayacnephia Wygodzinsky and Coscarón (1), Metacnephia Crosskey (3), Prosimulium Roubaud (12), Simulium Latreille (29), Stegopterna Enderlein (1), and Twinnia Stone and Jamnback (1). An annotated list summarizes what is known about the bionomics and distribution of each species in the province, including notes on their medical and veterinary importance, where applicable. Illustrated keys to the larvae and pupae of Alberta genera and species are provided. Also included in the keys are 3 species that may occur in the province (one of these in the genus Greniera Doby and David), but whose presence has yet to be verified. A review of some structural characters used for the identification of immature stages of black flies is given. Notes on nomenclature of some characters are also provided. A total of 188 figures, including detailed distribution maps for each species in Alberta, are given.