In this work, the composition of the superfamily Callianassoidea is reassessed and the classification of its included taxa is critically reviewed. The material examined mainly originates from the collections of the Zoological Museum of the University of Copenhagen, and comprises samples from the Galathea Expedition 1950-1952, Dr. Th. Mortensen’s expeditions, including the Java-South African Expedition 1929-1930, and Dr. G. Thorson’s Persian expedition. In all, three of the possibly five families currently incorporated in the Callianassoidea, i.e., Callianassidae, Gourretiidae, and Ctenochelidae, with a total of 12 subfamilies, 20 genera, and 219 species, are represented in this comprehensive revision. The status of the various taxa recognized is placed in the broader context of a re-evaluation of the contents of the infraorder Thalassinidea, in which characters derived from the anatomy of the gastric mill may play a pivotal role. The contents of the book are not only of interest for systematists but also for ecologists and environmental biologists focusing on neritic and benthic biocoenoses, as these mud shrimps are important agents in bioturbation processes of the sea floor.