This book presents an ecological approach on the diversity of Vespoidea (excluding Formicidae) in the Atlantic Rain Forest, one of the most diverse and most threatened ecosystems of the world. The Vespoidea have fundamental roles in ecosystem dynamics, being koinobiont and idiobiont parasitoids, predators, and cleptoparasitoids of different Arthropod taxa. Moreover, most of them act as pollinators when visiting flowers, seeking nectar. Our aim was to know the assemblage structure of the Vespoidea along an elevational gradient in the Atlantic Rain Forest. Together latitudinal gradient, elevational gradients are the major generators of biodiversity in the Atlantic Rain Forest. It has been suggested that stochastic forces are the main responsible for the species richness patterns, which may be influenced by historical and biotic factors. Thus, in our study it was applied different analytical methods, regarding taxonomic and functional apsects of Vespoidea. The results presented here may be used as basis for new studies in the Atlantic Forest and may help conservation strategies.