A supraspecific revision of the three superfamilies of feather mites, Analgoidea, Freyanoidea and Pterolichoidea. Topics include host specificity, criteria for feather mite classification, morphology, intraspecific polymorphism, history of classification, collecting methods and a bibliography. The systematic section gives a key to the 33 families, a brief summary of each family and subfamily, keys to the genera of each family and subfamily, establishment of numerous new genera and illustrations of representative species for 441 of the 444 included genera.