Lauri Honko (1932-2002), the Finnish professor of folkloristics and comparative religion was a prolific and multitalented researcher, whose topics of research ranged from the study of folk beliefs, folk medicine and Ingrian laments to the general theories of culture, identity and meaning. He studied Finno-Ugric mythologies, Karelian and Tanzanian folk healing, and South Indian oral traditions. In this book we aim at explicating and analyzing his methodological assumptions as well as his specific theoretical contributions in the study of religion and folklore. Our central focus is on Honko’s tradition ecology, an approach to cultural systems that exposes their dynamic and functionalistic features. We compare and contrast tradition ecology with other theories in religious studies and folkloristics, especially with those theories that stem from the evolutionary and cognitive paradigms. Furthermore, we will explicate Honko’s programmatic model of the folklore process, by means of which the dynamics of religions and folklore can be conceptually captured. We argue that Honko had a coherent theory of culture, where functionalism played the central role. His views on folklore and religion were dependent on that theory. Furthermore, we argue that in Honko’s theory, religious studies needs methodological support from folkloristics.