| Acanthaspidiidae Just, 2001 | | 46 | Species | Taxom |
| Acanthogammaridae Garjajeff, 1901 | | 63 | Species | Taxom |
| Acanthonotozomatidae (Stebbing, 1906) | | 1 | Species | Taxom |
| Acanthonotozomellidae Coleman & Ba..., 1991 | | 10 | Species | Taxom |
| Acidostomatidae Stoddart & L..., 2012 | | 1 | Species | Taxom |
| Actaeciidae Vandel, 1952 | | 10 | Species | Taxom |
| Aegidae White, 1850 | | 210 | Species | Taxom |
| Agathotanaidae Lang, 1971 | | 39 | Species | Taxom |
| Agnaridae Schmidt, 2003 | | 1 | Species | Taxom |
| Akanthophoreidae Sieg, 1986 | | 24 | Species | Taxom |
| Alavatanaidae Vonk & Schram, 2007 | | 4 | Species | Taxom |
| Alicellidae Lowry & De B..., 2008 | | 0 | Species | Taxom |
| Allocrangonyctidae Holsinger, 1989 | | 71 | Species | Taxom |
| Alloniscidae Schmidt, 2003 | | 27 | Species | Taxom |
| Amaryllididae Lowry & Stod..., 2002 | | 37 | Species | Taxom |
| Amathillopsidae Pirlot, 1934 | | 20 | Species | Taxom |
| Ampeliscidae Costa, 1857 | | 259 | Species | Taxom |
| Amphilochidae Boeck, 1871 | | 105 | Species | Taxom |
| Amphisopodidae Nicholls, 1943 | | 27 | Species | Taxom |
| Amphithyridae Zeidler, 2016 | | 1 | Species | Taxom |
| Ampithoidae J. L. Barnard, 1965 | | 248 | Species | Taxom |
| Anapronoidae Bowman & Gruner, 1973 | | 2 | Species | Taxom |
| Anarthruridae Lang, 1971 | | 17 | Species | Taxom |
| Ancinidae Tattersall, 1905 | | 14 | Species | Taxom |
| Anisogammaridae Bousfield, 1977 | | 53 | Species | Taxom |
| Antarcturidae Kussakin & V..., 1998 | | 51 | Species | Taxom |
| Antheluridae Kensley & Sc..., 2000 | | 23 | Species | Taxom |
| Anthracocarididae Schram, 1979 | | 4 | Species | Taxom |
| Anthuridae Wägele, 1982 | | 345 | Species | Taxom |
| Anuropidae Stebbing, 1893 | | 6 | Species | Taxom |
| Aoridae Shoemaker, 1945 | | 279 | Species | Taxom |
| Apseudellidae Gutu, 1972 | | 1 | Species | Taxom |
| Apseudidae Leach, 1814 | | 177 | Species | Taxom |
| Archaeoniscidae Haack, 1918 | | 4 | Species | Taxom |
| Archaeoscinidae Stebbing, 1904 | | 2 | Species | Taxom |
| Arcitalitridae Myers & Lowry, 2020 | | 17 | Species | Taxom |
| Arcturidae Dana, 1849 | | 270 | Species | Taxom |
| Arcturididae Poore, 2001 | | 3 | Species | Taxom |
| Argissidae Walker, 1904 | | 3 | Species | Taxom |
| Aristiidae Lowry & Stod..., 1997 | | 33 | Species | Taxom |
| Armadillidae Brandt, 1831 | | 946 | Species | Taxom |
| Armadillidiidae Brandt, 1833 | Doodle bugs | 328 | Species | Taxom |
| Artesiidae Holsinger, 1980 | | 7 | Species | Taxom |
| Asconiscidae Bonnier, 1900 | | 1 | Species | Taxom |
| Asellidae Latreille, 1802 | Freshwater Isopods | 437 | Species | Taxom |
| Atlantasellidae Sket, 1979 | | 2 | Species | Taxom |
| Atylidae Lilljeborg, 1865 | | 73 | Species | Taxom |
| Australomicroprotopidae Myers, Lowry..., 2016 | | 1 | Species | Taxom |
| Austrarcturellidae Poore & Bard..., 1992 | | 19 | Species | Taxom |
| Austroniphargidae Iannilli, Kr..., 2011 | | 2 | Species | Taxom |
| Baikalogammaridae Kamaltynov, 2001 | | 1 | Species | Taxom |
| Balloniscidae Araujo & Zaido, 1995 | | 11 | Species | Taxom |
| Barybrotidae Hansen, 1890 | | 1 | Species | Taxom |
| Bateidae Stebbing, 1906 | | 17 | Species | Taxom |
| Bathynataliidae Poore, 2005 | | 4 | Species | Taxom |
| Bathytropidae Vandel, 1952 | | 31 | Species | Taxom |
| Behningiellidae Kamaltynov, 2001 | | 2 | Species | Taxom |
| Berytoniscidae Vandel, 1973 | | 1 | Species | Taxom |
| Biancolinidae Barnard, 1972 | | 6 | Species | Taxom |
| Bodotriidae T. Scott, 1901 | | 388 | Species | Taxom |
| Bogidiellidae Hertzog, 1936 | | 93 | Species | Taxom |
| Bolttsiidae Barnard & Ka..., 1987 | | 2 | Species | Taxom |
| Bopyridae Rafinesque, 1815 | | 685 | Species | Taxom |
| Bougisidae Zeidler, 2004 | | 1 | Species | Taxom |
| Brachyscelidae Stephensen, 1923 | | 1 | Species | Taxom |
| Buddelundiellidae (G. O. Sars, 1899) | | 20 | Species | Taxom |
| Cabiropidae Giard & Bonnier, 1887 | | 25 | Species | Taxom |
| Calabozoidae Van Lieshout, 1983 | | 1 | Species | Taxom |
| Calliopiidae G. O. Sars, 1895 | | 122 | Species | Taxom |
| Capitoniscidae Boyko & Will..., 2023 | | 3 | Species | Taxom |
| Caprellidae Leach, 1814 | Ghost shrimps | 318 | Species | Taxom |
| Caprogammaridae Kudrjaschov ..., 1966 | | 1 | Species | Taxom |
| Carangoliopsidae Bousfield, 1977 | | 1 | Species | Taxom |
| Cardenioidae Barnard & Ka..., 1987 | | 1 | Species | Taxom |
| Caudalongidae Błażewicz & ..., 2024 | | 2 | Species | Taxom |
| Cebocaridae Lowry & Stod..., 2011 | | 1 | Species | Taxom |
| Ceinidae J. L. Barnard, 1972 | | 21 | Species | Taxom |
| Ceratocumatidae Calman, 1905 | | 11 | Species | Taxom |
| Chaetiliidae Dana, 1849 | | 50 | Species | Taxom |
| Cheidae Thurston, 1982 | | 3 | Species | Taxom |
| Cheirocratidae Ren, 2006 | | 4 | Species | Taxom |
| Cheluridae Allman, 1847 | | 4 | Species | Taxom |
| Chevaliidae Myers & Lowry, 2003 | | 1 | Species | Taxom |
| Chillagoeidae Lowry & Myers, 2012 | | 1 | Species | Taxom |
| Chiltoniidae Barnard, 1972 | | 6 | Species | Taxom |
| Chuneolidae Woltereck, 1909 | | 2 | Species | Taxom |
| Cirolanidae Dana, 1852 | Cave Isopods | 605 | Species | Taxom |
| Clarenciidae Barnard & Ka..., 1987 | | 1 | Species | Taxom |
| Colletteidae Larsen & Wilson, 2002 | | 54 | Species | Taxom |
| Colomastigidae Stebbing, 1899 | | 44 | Species | Taxom |
| Colypuridae Richardson, 1905 | | 1 | Species | Taxom |
| Condukiidae Barnard & Dr..., 1982 | | 1 | Species | Taxom |
| Conicostomatidae Lowry & Stod..., 2012 | | 4 | Species | Taxom |
| Corallanidae Nunomura, 2006 | | 92 | Species | Taxom |
| Corophiidae Leach, 1814 | | 143 | Species | Taxom |
| Crangonyctidae Bousfield, 1973 | Gammarid amphipods | 232 | Species | Taxom |
| Crangoweckeliidae Lowry & Myers, 2012 | | 3 | Species | Taxom |
| Cressidae Stebbing, 1899 | | 10 | Species | Taxom |
| Cretitanaidae Schram, Sieg..., 1986 | | 1 | Species | Taxom |
| Crymostygiidae Kristjánsson..., 2004 | | 1 | Species | Taxom |
| Cryptoniscidae Kossmann, 1880 | | 29 | Species | Taxom |
| Crypturopodidae Kamaltynov, 2002 | | 15 | Species | Taxom |
| Cyamidae Rafinesque, 1815 | Whale lice | 33 | Species | Taxom |
| Cylisticidae Verhoeff, 1949 | | 71 | Species | Taxom |
| Cyllopodidae Bovallius, 1887 | | 2 | Species | Taxom |
| Cymothoidae Leach, 1818 | Fish Doctors | 404 | Species | Taxom |
| Cyphocarididae Lowry & Stod..., 1997 | | 17 | Species | Taxom |
| Cyproideidae J. L. Barnard, 1974 | | 36 | Species | Taxom |
| Cyproniscidae Giard & Bonnier, 1887 | | 8 | Species | Taxom |
| Cystisomatidae Willemöes-Suhm, 1875 | | 10 | Species | Taxom |
| Dairellidae Bovallius, 1887 | | 2 | Species | Taxom |
| Dajidae Giard & Bonnier, 1887 | | 47 | Species | Taxom |
| Delatorreidae Verhoeff, 1938 | | 1 | Species | Taxom |
| Dendrotiidae (Vanhöffen, 1914) | | 16 | Species | Taxom |
| Dendrotionidae (Cohen, 1998) | | 1 | Species | Taxom |
| Derjugianidae Lowry & Myers, 2017 | | 1 | Species | Taxom |
| Desmosomatidae Brix, 2006 | | 145 | Species | Taxom |
| Dexaminidae Leach, 1814 | | 89 | Species | Taxom |
| Diastylidae Bate, 1856 | | 318 | Species | Taxom |
| Didymocheliidae Bellan-Santi..., 1986 | | 2 | Species | Taxom |
| Dikwidae Coleman & Ba..., 1991 | | 1 | Species | Taxom |
| Dogielinotidae Gurjanova, 1953 | | 46 | Species | Taxom |
| Dubioniscidae Vandel, 1953 | | 50 | Species | Taxom |
| Dulichiidae Dana, 1849 | | 2 | Species | Taxom |
| Echinothambematidae Menzies, 1962 | | 1 | Species | Taxom |
| Endevouridae Lowry & Stod..., 1997 | | 14 | Species | Taxom |
| Entoniscidae Kossmann, 1881 | | 27 | Species | Taxom |
| Eophliantidae Sheard, 1936 | | 12 | Species | Taxom |
| Epimeriidae Boeck, 1871 | | 73 | Species | Taxom |
| Eriopisidae Lowry & Myers, 2013 | | 45 | Species | Taxom |
| Eubelidae Taiti, Ferra..., 2000 | | 264 | Species | Taxom |
| Eucopiidae Sars, 1885 | | 9 | Species | Taxom |
| Eulimnogammaridae Kamaltynov, 1999 | | 45 | Species | Taxom |
| Eurytheneidae Stoddart & L..., 2004 | | 0 | Species | Taxom |
| Eusiridae Stebbing, 1888 | | 204 | Species | Taxom |
| Exoedicerotidae Barnard & Dr..., 1982 | | 20 | Species | Taxom |
| Expanathuridae Nunomura, 1984 | | 63 | Species | Taxom |
| Falklandellidae Lowry & Myers, 2012 | | 3 | Species | Taxom |
| Gammaracanthidae Bousfield, 1989 | | 5 | Species | Taxom |
| Gammarellidae Bousfield, 1977 | | 11 | Species | Taxom |
| Gammaridae Leach, 1813 | Gammarids | 510 | Species | Taxom |
| Gammaroporeiidae Bousfield, 1979 | | 1 | Species | Taxom |
| Gigantapseudidae Kudinova-Pas..., 1978 | | 2 | Species | Taxom |
| Giniphargidae Lowry & Myers, 2012 | | 1 | Species | Taxom |
| Gnathiidae Leach, 1814 | | 250 | Species | Taxom |
| Gnathophausiidae Udrescu, 1984 | | 17 | Species | Taxom |
| Gnathostenetroididae Kussakin, 1967 | | 21 | Species | Taxom |
| Gynodiastylidae Stebbing, 1912 | | 110 | Species | Taxom |
| Hadromastacidae Bruce & Müller, 1991 | | 3 | Species | Taxom |
| Hadziidae Karaman, 1943 | | 99 | Species | Taxom |
| Halophilosciidae Verhoeff, 1908 | | 38 | Species | Taxom |
| Hamatipedidae Błażewicz, G..., 2022 | | 2 | Species | Taxom |
| Haplomunnidae Wilson, 1976 | | 12 | Species | Taxom |
| Haploniscidae Hansen, 1916 | | 115 | Species | Taxom |
| Haustoriidae Stebbing, 1906 | | 48 | Species | Taxom |
| Hekelidae Ferrara, 1977 | | 1 | Species | Taxom |
| Hemioniscidae (Bonnier, 1900) | | 5 | Species | Taxom |
| Hirsutiidae Sanders, Hes..., 1985 | | 5 | Species | Taxom |
| Holidoteidae Wägele, 1989 | | 14 | Species | Taxom |
| Holognathidae G. Thomson, 1904 | | 31 | Species | Taxom |
| Hyalellidae Gurjanova, 1953 | | 50 | Species | Taxom |
| Hyalidae Bulycheva, 1957 | | 161 | Species | Taxom |
| Hyperiidae Dana, 1853 | Hyperiids | 57 | Species | Taxom |
| Hyperiopsidae Bovallius, 1886 | | 3 | Species | Taxom |
| Hypsimetopidae Nicholls, 1943 | | 2 | Species | Taxom |
| Hypsimetopodidae Nicholls, 1943 | | 7 | Species | Taxom |
| Hyssuridae Wägele, 1981 | | 43 | Species | Taxom |
| Iciliidae Dana, 1849 | | 7 | Species | Taxom |
| Idoteidae Samouelle, 1819 | | 248 | Species | Taxom |
| Ingolfiellidae Hansen, 1903 | | 29 | Species | Taxom |
| Ipanemidae Barnard & Th..., 1988 | | 1 | Species | Taxom |
| Iphimediidae Boeck, 1871 | | 106 | Species | Taxom |
| Irmaosidae Ferrara & Taiti, 1983 | | 2 | Species | Taxom |
| Isaeidae Dana, 1853 | | 229 | Species | Taxom |
| Ischnomesidae Hansen, 1916 | | 115 | Species | Taxom |
| Ischyroceridae Stebbing, 1899 | | 273 | Species | Taxom |
| Iulopididae Zeidler, 2004 | | 1 | Species | Taxom |
| Izinkalidae Lowry & Stod..., 2010 | | 1 | Species | Taxom |
| Jaeropsidae (Nordenstam, 1933) | | 8 | Species | Taxom |
| Janirellidae Menzies, 1956 | | 33 | Species | Taxom |
| Janiridae Sars, 1897 | | 175 | Species | Taxom |
| Joeropsididae Nordenstam, 1933 | | 77 | Species | Taxom |
| Julmarichardiidae Moralés-Núñe..., 2021 | | 4 | Species | Taxom |
| Jurapseudidae Schram, Sieg..., 1986 | | 2 | Species | Taxom |
| Kalliapseudidae Lang, 1956 | | 50 | Species | Taxom |
| Kamakidae Myers & Lowry, 2003 | | 17 | Species | Taxom |
| Katianiridae Svavarsson, 1987 | | 7 | Species | Taxom |
| Kergueleniidae Lowry & Stod..., 2010 | | 4 | Species | Taxom |
| Kergueleniolidae Lowry & Myers, 2013 | | 1 | Species | Taxom |
| Keuphyliidae Bruce, 1980 | | 1 | Species | Taxom |
| Lafystiidae Krøyer, 1842 | | 6 | Species | Taxom |
| Lampropidae Sars, 1878 | | 147 | Species | Taxom |
| Lanceolidae Bovallius, 1887 | | 25 | Species | Taxom |
| Laphystiopsidae Stebbing, 1899 | | 7 | Species | Taxom |
| Lepechinellidae Schellenberg, 1926 | | 5 | Species | Taxom |
| Lepidocharontidae Galassi & Bruce, 2016 | | 2 | Species | Taxom |
| Lepidomysidae Clarke, 1961 | | 9 | Species | Taxom |
| Leptanthuridae Poore, 2001 | | 103 | Species | Taxom |
| Leptocheliidae Lang, 1973 | | 149 | Species | Taxom |
| Leptognathiidae Sieg, 1976 | | 63 | Species | Taxom |
| Lestrigonidae Zeidler, 2004 | | 21 | Species | Taxom |
| Leuconidae Sars, 1878 | | 156 | Species | Taxom |
| Leucothoidae Dana, 1852 | | 161 | Species | Taxom |
| Ligiidae Leach, 1814 | Rock lice | 117 | Species | Taxom |
| Liljeborgiidae Stebbing, 1899 | | 107 | Species | Taxom |
| Limnoriidae White, 1850 | Gribble | 63 | Species | Taxom |
| Lophogastridae Sars, 1870 | | 27 | Species | Taxom |
| Luciobliviidae Tomikawa, 2007 | | 1 | Species | Taxom |
| Lycaeidae Claus, 1879 | | 27 | Species | Taxom |
| Lycaeopsidae Chevreux, 1913 | | 4 | Species | Taxom |
| Lysianassidae Dana, 1849 | | 736 | Species | Taxom |
| Macrohectopidae Sowinsky, 1915 | | 1 | Species | Taxom |
| Macrostylidae Hansen, 1916 | | 51 | Species | Taxom |
| Maeridae Krapp-Schickel, 2008 | | 88 | Species | Taxom |
| Makawidae Myers & Lowry, 2020 | | 5 | Species | Taxom |
| Maxillipiidae Ledoyer, 1973 | | 2 | Species | Taxom |
| Megalanceolidae Zeidler, 2009 | | 1 | Species | Taxom |
| Megaluropidae Thomas & Bar..., 1987 | | 16 | Species | Taxom |
| Melitidae Bousfield, 1973 | | 442 | Species | Taxom |
| Melphidippidae Stebbing, 1899 | | 23 | Species | Taxom |
| Mesogammaridae Bousfield, 1977 | | 4 | Species | Taxom |
| Mesoniscidae Verhoeff, 1908 | | 7 | Species | Taxom |
| Mesosignidae Schultz, 1969 | | 16 | Species | Taxom |
| Metacrangonyctidae Boutin & Mis..., 1988 | | 7 | Species | Taxom |
| Metaingolfiellidae Ruffo, 1969 | | 1 | Species | Taxom |
| Metapseudidae Lang, 1970 | | 49 | Species | Taxom |
| Microcerberidae Karaman, 1933 | | 55 | Species | Taxom |
| Microniscidae | | 1 | Species | Taxom |
| Microparasellidae Karaman, 1933 | | 78 | Species | Taxom |
| Microphasmatidae (Stephensen &..., 1931) | | 7 | Species | Taxom |
| Micruropodidae Kamaltynov, 1999 | | 21 | Species | Taxom |
| Mictocarididae Bowman & Iliffe, 1985 | | 1 | Species | Taxom |
| Mictosomatidae Wolff, 1965 | | 1 | Species | Taxom |
| Mimonectidae Bovallius, 1885 | | 10 | Species | Taxom |
| Miramarassidae Lowry, 2006 | | 1 | Species | Taxom |
| Mirandotanaidae Blazewicz-Pa..., 2009 | | 3 | Species | Taxom |
| Munnidae Sars, 1897 | | 111 | Species | Taxom |
| Munnopsidae Lilljeborg, 1864 | | 403 | Species | Taxom |
| Mysidae Haworth, 1825 | | 1112 | Species | Taxom |
| Najnidae Barnard, 1972 | | 13 | Species | Taxom |
| Nannastacidae Spence Bate, 1866 | | 526 | Species | Taxom |
| Nannoniscidae Hansen, 1916 | | 80 | Species | Taxom |
| Neomegamphopidae Myers, 1981 | | 11 | Species | Taxom |
| Neoniphargidae Bousfield, 1977 | | 25 | Species | Taxom |
| Neotanaidae Lang, 1956 | | 45 | Species | Taxom |
| Nihotungidae J.L. Barnard, 1972 | | 2 | Species | Taxom |
| Niphargidae Bousfield, 1977 | | 284 | Species | Taxom |
| Nototanaidae Sieg, 1976 | | 100 | Species | Taxom |
| Numbakullidae Gutu & Heard, 2002 | | 3 | Species | Taxom |
| Ochlesidae Stebbing, 1910 | | 19 | Species | Taxom |
| Odiidae Coleman & Ba..., 1991 | | 14 | Species | Taxom |
| Oedicerotidae Lilljeborg, 1865 | | 236 | Species | Taxom |
| Olibrinidae Vandel, 1973 | | 24 | Species | Taxom |
| Ommatogammaridae Kamaltynov, 2010 | | 7 | Species | Taxom |
| Oniscidae Latreille, 1802 | Sow Bugs | 71 | Species | Taxom |
| Opisidae Lowry & Stod..., 1995 | | 22 | Species | Taxom |
| Orithopsidae Schweitzer, ..., 2003 | | 5 | Species | Taxom |
| Otagiidae Hughes & Lörz, 2013 | | 2 | Species | Taxom |
| Oxycephalidae Dana, 1852 | | 27 | Species | Taxom |
| Pachyschesidae Kamaltynov, 1999 | | 2 | Species | Taxom |
| Pagetinidae K.H. Barnard, 1931 | | 4 | Species | Taxom |
| Pagurapseudidae Lang, 1970 | | 23 | Species | Taxom |
| Pakynidae Lowry & Myers, 2017 | | 27 | Species | Taxom |
| Palaeophreatoicidae Birshtein, 1962 | | 4 | Species | Taxom |
| Pallaseidae Tachteew, 2000 | | 20 | Species | Taxom |
| Paracalliopiidae Barnard & Ka..., 1982 | | 22 | Species | Taxom |
| Paracrangonyctidae Bousfield, 1983 | | 2 | Species | Taxom |
| Paragammaropsidae Myers & Lowry, 2003 | | 1 | Species | Taxom |
| Paramelitidae Bousfield, 1977 | | 51 | Species | Taxom |
| Paramunnidae Vanhöffen, 1914 | | 183 | Species | Taxom |
| Paranarthrurellidae Błażewicz, J..., 2019 | | 0 | Species | Taxom |
| Paranthuridae Menzies & Glynn, 1968 | | 99 | Species | Taxom |
| Paraphronimidae Bovallius, 1887 | | 2 | Species | Taxom |
| Paraplatyarthridae Javidkar & King, 2015 | | 7 | Species | Taxom |
| Parapseudidae Gutu, 1981 | | 59 | Species | Taxom |
| Parascelidae Bovallius, 1887 | | 13 | Species | Taxom |
| Paratanaidae Lang, 1949 | | 48 | Species | Taxom |
| Pardaliscidae Boeck, 1871 | | 63 | Species | Taxom |
| Pariambidae (Leach, 1814) | Ghost shrimps | 1 | Species | Taxom |
| Peachocarididae Schram, 1986 | | 2 | Species | Taxom |
| Periscyphicidae Ferrara, 1973 | | 1 | Species | Taxom |
| Perthiidae Williams & J..., 1988 | | 2 | Species | Taxom |
| Petalophthalmidae Czerniavsky, 1882 | | 29 | Species | Taxom |
| Philosciidae Kinahan, 1857 | Woodlice | 665 | Species | Taxom |
| Phliantidae Stebbing, 1899 | | 29 | Species | Taxom |
| Phoratopodidae Hale, 1925 | | 1 | Species | Taxom |
| Photidae (Boeck, 1871) | | 16 | Species | Taxom |
| Phoxocephalidae Sars, 1891 | | 365 | Species | Taxom |
| Phoxocephalopsidae Barnard & Dr..., 1982 | | 8 | Species | Taxom |
| Phreatogammaridae Bousfield, 1982 | | 5 | Species | Taxom |
| Phreatoicidae Chilton, 1891 | | 61 | Species | Taxom |
| Phronimidae Rafinesque, 1815 | | 14 | Species | Taxom |
| Phrosinidae Dana, 1852 | | 10 | Species | Taxom |
| Plakarthriidae Hansen, 1905 | | 3 | Species | Taxom |
| Plakathriidae | | 1 | Species | Taxom |
| Platyarthridae Verhoeff, 1949 | Woodlice | 139 | Species | Taxom |
| Platyischnopidae Barnard & Dr..., 1979 | | 21 | Species | Taxom |
| Platyscelidae Bate, 1862 | | 24 | Species | Taxom |
| Pleioplateidae Barnard, 1978 | | 1 | Species | Taxom |
| Pleopteryxidae Schweigert &..., 2006 | | 1 | Species | Taxom |
| Pleurocopidae Fresi & Schi..., 1972 | | 8 | Species | Taxom |
| Pleustidae Bucholz, 1874 | | 133 | Species | Taxom |
| Podasconidae Giard & Bonnier, 1895 | | 3 | Species | Taxom |
| Podoceridae Leach, 1814 | | 110 | Species | Taxom |
| Podoprionidae Lowry & Stod..., 1996 | | 1 | Species | Taxom |
| Ponderellidae Wilson and K..., 2004 | | 2 | Species | Taxom |
| Pontogammaridae Bousfield, 1977 | | 10 | Species | Taxom |
| Pontogeneiidae Stebbing, 1906 | | 46 | Species | Taxom |
| Pontoporeiidae Dana, 1853 | | 42 | Species | Taxom |
| Porcellionidae Brandt & Rat..., 1831 | Woodlice | 574 | Species | Taxom |
| Priscomilitaridae Hirayama, 1988 | | 1 | Species | Taxom |
| Pronoidae Dana, 1852 | | 17 | Species | Taxom |
| Proscinidae Pirlot, 1933 | | 7 | Species | Taxom |
| Protognathiidae Wägele & Bra..., 1988 | | 2 | Species | Taxom |
| Protojaniridae Fresi, Idat..., 1980 | | 11 | Species | Taxom |
| Protorchestiidae Myers & Lowry, 2020 | | 15 | Species | Taxom |
| Psammaspidae | | 1 | Species | Taxom |
| Pseudamphilochidae Schellenberg, 1931 | | 1 | Species | Taxom |
| Pseudarmadillidae Vandel, 1973 | | 17 | Species | Taxom |
| Pseudidotheidae Ohlin, 1901 | | 5 | Species | Taxom |
| Pseudingolfiellidae Lowry & Myers, 2012 | | 1 | Species | Taxom |
| Pseudocrangonyctidae Holsinger, 1989 | | 16 | Species | Taxom |
| Pseudocumatidae G. O. Sars, 1878 | | 33 | Species | Taxom |
| Pseudojaniridae Wilson, 1986 | | 9 | Species | Taxom |
| Pseudotanaidae Sieg, 1976 | | 54 | Species | Taxom |
| Pseudozeuxidae Sieg, 1982 | | 2 | Species | Taxom |
| Pudeoniscidae Lemos de Castro, 1973 | | 7 | Species | Taxom |
| Rakiroidae Myers & Lowry, 2003 | | 1 | Species | Taxom |
| Rectarcturidae Poore, 2001 | | 7 | Species | Taxom |
| Rhabdochiridae Richardson, 1905 | | 1 | Species | Taxom |
| Rhinocarididae Hall & Clarke, 1888 | | 15 | Species | Taxom |
| Rhyscotidae Budde-Lund, 1908 | | 24 | Species | Taxom |
| Salentinellidae Bousfield, 1977 | | 14 | Species | Taxom |
| Sanchoidae Lowry, 2006 | | 2 | Species | Taxom |
| Santiidae Wilson, 1987 | | 36 | Species | Taxom |
| Schoebliidae Verhoeff, 1938 | | 2 | Species | Taxom |
| Scinidae Stebbing, 1888 | | 40 | Species | Taxom |
| Scleropactidae Verhoeff, 1938 | | 73 | Species | Taxom |
| Scopelocheiridae Lowry & Stod..., 1997 | | 19 | Species | Taxom |
| Scyphacidae Dana, 1852 | | 75 | Species | Taxom |
| Sebidae Walker, 1908 | | 28 | Species | Taxom |
| Seborgiidae Holsinger, 1980 | | 1 | Species | Taxom |
| Serolidae Dana, 1852 | | 158 | Species | Taxom |
| Sicafodiidae Just, 2004 | | 2 | Species | Taxom |
| Spelaeogriphidae Gordon, 1957 | | 5 | Species | Taxom |
| Spelaeoniscidae Vandel, 1948 | | 19 | Species | Taxom |
| Sphaeromapseudidae Larsen, 2011 | | 1 | Species | Taxom |
| Sphaeromatidae Latreille, 1825 | | 797 | Species | Taxom |
| Sphaeroniscidae Vandel, 1964 | | 48 | Species | Taxom |
| Sphyrapidae Gutu, 1980 | | 16 | Species | Taxom |
| Sphyrapodidae Gutu, 1980 | | 3 | Species | Taxom |
| Stegocephalidae Dana, 1852 | | 101 | Species | Taxom |
| Stenasellidae Dudich, 1924 | | 69 | Species | Taxom |
| Stenetriidae Hansen, 1905 | | 109 | Species | Taxom |
| Stenoniscidae Budde-Lund, 1904 | | 6 | Species | Taxom |
| Stenothoidae Boeck, 1871 | | 291 | Species | Taxom |
| Sternophysingidae Holsinger, 1992 | | 3 | Species | Taxom |
| Stilipididae Holmes, 1908 | | 20 | Species | Taxom |
| Stygiomysidae Caroli, 1937 | | 5 | Species | Taxom |
| Styloniscidae Vandel, 1952 | | 91 | Species | Taxom |
| Synopiidae Dana, 1852 | | 78 | Species | Taxom |
| Tainisopidae Wilson, 2003 | | 7 | Species | Taxom |
| Talitridae Rafinesque, 1815 | Beach Hoppers | 351 | Species | Taxom |
| Tanaellidae Larsen & Wilson, 2002 | | 47 | Species | Taxom |
| Tanaidae Dana, 1849 | | 103 | Species | Taxom |
| Tanaididae (Dana, 1849) | | 1 | Species | Taxom |
| Tanaissuidae Bird & Larsen, 2009 | | 3 | Species | Taxom |
| Tanaopsidae B& 322;a& 38..., 2012 | | 1 | Species | Taxom |
| Tanzanapseudidae Bacescu, 1975 | | 6 | Species | Taxom |
| Tecticipitidae Bruce, 1993 | | 7 | Species | Taxom |
| Temnophliantidae Griffiths, 1975 | | 2 | Species | Taxom |
| Tendosphaeridae Verhoeff, 1930 | | 6 | Species | Taxom |
| Thambematidae Stebbing, 1913 | | 5 | Species | Taxom |
| Thoriellidae Lowry & Stod..., 2011 | | 6 | Species | Taxom |
| Thurstonellidae Lowry & Zeidler, 2008 | | 1 | Species | Taxom |
| Titaniidae Verhoeff, 1938 | | 6 | Species | Taxom |
| Torynommatidae | | 1 | Species | Taxom |
| Trachelipodidae Strouhal, 1953 | | 333 | Species | Taxom |
| Trichoniscidae G. O. Sars, 1899 | Woodlice | 656 | Species | Taxom |
| Tridentellidae Bruce, 1984 | | 24 | Species | Taxom |
| Tryphosidae (Lowry & Stod..., 1997) | | 0 | Species | Taxom |
| Turanoniscidae Borutzkii, 1969 | | 1 | Species | Taxom |
| Tylidae Dana, 1852 | | 31 | Species | Taxom |
| Typhlogammaridae Bousfield, 1977 | | 6 | Species | Taxom |
| Typhlotanaidae (Sieg, 1986) | | 22 | Species | Taxom |
| Tyronidae Bovallius, 1887 | | 2 | Species | Taxom |
| Udorellidae | | 1 | Species | Taxom |
| Unciolidae Myers & Lowry, 2003 | | 7 | Species | Taxom |
| Urdidae Kunth, 1870 | | 2 | Species | Taxom |
| Uristidae Hurley, 1963 | | 205 | Species | Taxom |
| Urohaustoriidae Barnard & Dr..., 1982 | | 23 | Species | Taxom |
| Uronyctidae Lowry & Myers, 2012 | | 1 | Species | Taxom |
| Urothoidae Bousfield, 1978 | | 49 | Species | Taxom |
| Urstylidae Riehl, Wilso..., 2014 | | 2 | Species | Taxom |
| Valettidae Stebbing, 1888 | | 1 | Species | Taxom |
| Valettiopsidae Lowry & De B..., 2008 | | 4 | Species | Taxom |
| Vermectiadidae Just & Poore, 1992 | | 1 | Species | Taxom |
| Vibiliidae Dana, 1852 | | 22 | Species | Taxom |
| Wandinidae Lowry & Stod..., 1990 | | 3 | Species | Taxom |
| Whiteleggiidae Gutu, 1972 | | 4 | Species | Taxom |
| Xandarocarcinidae | | 1 | Species | Taxom |
| Xenarcturidae Sheppard, 1957 | | 1 | Species | Taxom |
| Xenosellidae Just, 2005 | | 1 | Species | Taxom |
| Zobrachoidae Barnard & Dr..., 1982 | | 7 | Species | Taxom |
