This work treats 135 species of Histeridae recorded from Canada as well as 11 that could occur in the country. Seven new species are described. This monograph includes keys to subfamilies, genera, and species studied. For each species, the following is provided: a list of North American synonyms, a selective list of references, a diagnosis and a description, notes on the geographical distribution and data on the habitat. Distribution maps and illustrations of taxonomic characters for a number of species are included, as well as habitus drawings of representative species.