Alkaline magmas are an uncommon but intriguing member of many of the Earth's volcanic arc systems. This peculiar magmatism is generally associated with perturbations to the “normal” tectonic setting of arc magmatism. In December 1986, we convened a symposium at the AGU Fall Meeting to explore connections between the tectonic environments of alkaline arc magmatism and specific petrologic processes associated with their genesis. Twenty‐five contributions reported occurrences of alkaline arc magmas, including modern and ancient examples from both intraoceanic and continental margin volcanic arcs.