More than one and a half centuries after the publication of Charles R. Darwin’s The Origin of Species, the identification of the processes governing the emergence of novel species remains a fundamental question to biology. Why is it that some groups have diversified in a seemingly explosive manner, while other lineages have remained unvaried over millions of years? What are the external factors and environmental conditions that promote diversification? And what is the molecular basis of adaptation, evolutionary innovation and diversification? Demonstrating particularly clear evidence of the power of natural selection, adaptive radiations emerge as outstanding systems for studying the mechanisms of evolution. The first wave of genomic investigation across major archetypal adaptive radiations – such as Darwin’s finches, anole lizards, threespine stickleback fish, and cichlid fishes in the East African Great Lakes – is starting to shed light on the molecular basis of adaptive diversification. Here, I provide an overview of genomic studies on adaptive radiations, with a particular focus on cichlid fish.