This special issue of Costa Rica’s premier biology journal, the Revista de Biología Tropical (Tropical Biology Journal) is dedicated to the Freshwater Macroinvertebrates of the country. Volume I (the only one published so far) includes detailed introductions to the freshwater ecosystems of Costa Rica, methods of study and collection, biomonitoring, and other techniques, as well as keys and descriptions of all known families and genera of freshwater mayflies (Ephemeroptera), stoneflies (Plecoptera), dragonflies and damselflies (Odonata) and tricópteros (Trichoptera). Volume II will concentrate on the orders Diptera, Coleoptera, Hemiptera, Megaloptera and the freshwater mites (Acari). Volume III will deal with freshwater mollusks. Copies of this publication can be downloaded as PDFs directly from the publisher at: http://rbt.biologia.ucr.ac.cr/pages/suppl/sup58-4.html