Hybridization often prevents speciation by causing gene flow between incipient sister species before the completion of speciation. However, recent genomic analyses of adaptive radiations have shed light on a different aspect of hybridization; hybridization between genetically distinct evolutionary lineages can sometimes promote rapid speciation and adaptive radiation. In this symposium, five speakers discuss about the evolutionary roles of hybridization in speciation and adaptive radiation. First, Kotaro Kagawa talks about our current theoretical understanding of speciation and adaptive radiation driven by hybridization. Then, four speakers talk about genomic and biogeographic studies of four adaptive radiations of fish. Dr. Emilie Richards talks about creative evolutionary roles of hybridization in an adaptive radiation of Caribbean pupfish. Dr. Ryo Kakioka talks about adaptive radiations of ricefish on the Sulawesi Island, in which contributions of ancient hybridization events have recently been demonstrated. Dr. Philine Feulner talks about genomic evolution caused by a recent human-mediated speciation reversal in an adaptive radiation of European whitefish. Finally, Prof. Ole Seehausen talks about how hybridization has contributed to shape the evolution of African cichlids, a model system of adaptive radiation. We hope that this symposium will be an opportunity to identify new questions for future research of this field.