A general introduction is provided to the natural history and external morphology for the following families of the Vespoidea: Tiphiidae, Mutillidae, Sapygidae, Scoliidae and Vespidae including the subfamilies Eumeninae, Polistinae and Vespinae. A checklist is given for the 45 species that have been recorded from the British Isles. Keys to the families, genera and species, together with diagnostic illustrations, are provided. Notes are given on the preparation of specimens for identification. Species profiles include information on British and overseas distribution, habitats, adult activity period, nesting characteristics, prey, host records and flowers visited.