The Federated States of Micronesia (FSM) consists of over 600 volcanic islands and coral atolls with some of the most extensive coral reefs in the Indo-Pacific. The archipelago is home to several hundred species of reef-building coral species, many of which are difficult to identify even by experts. This field guide to some of the most common corals in FSM provides a resource for coral reef scientists, managers, monitoring teams, and anyone else interested in learning about reef-building corals. Corals are presented in the conventional taxonomic order, because it puts corals that are morphologically similar together, which facilitates learning to distinguish them. A few modifications of that order have been introduced to help put similar looking species closer together. This guide presently has 80 species in 24 genera.