This book is an up-to-date synopsis of aquatic dance flies (Clinocerinae and Hemerodromiinae), insects that have been studied for more than 200 years in Europe. Its publication comes about 80 years since the last summary report and follows a period when new scientific methods were applied to long-standing unresolved taxonomical, systematic problems. In a period of environmental change, it also provides information for habitat conservation. The inclusion of data for larvae, pupae and adults is aimed not only at professional scientists, but will be of interest to amateur researchers. The work provides comprehensive information on the morphology, ecology, behavior, flight period and geographical distribution of individual species. Keys for males of all species together with drawings of terminalia are given, although females must still be associated with active males. Keys to larvae and pupae are provided wherever possible. Drawings and photographs of wings andmale terminalia are supplemented by photographs of larvae, pupae and adults of characteristic, widespread European species in their natural environment. The book covers the Central European Fauna and includes a few additional species from North Europe and Great Britain. Further, at the end of the presentation of every genus, all species described to date from all over Europe are listed so that people working in other European countries and even adjacent areas may get quick access to relevant information for their research and species identification. This is necessary because environmental change will affect distribution and abundance of genera and species restricted either to high-altitude mountains or to drying-up of streams and rivers.