This work presents a detailed study of two coral diseases currently prevalent on Indo-Pacific coral reefs. Black Band Disease (BBD) has been first reported from Caribbean reefs and has been investigated in this study on reefs in the Republic of Palau. White Syndrome (WS) has been reported from many locations on the Great Barrier Reef (GBR) and throughout the Indo-Pacific Ocean. This work identified causative agents for WS, which are all members of the Gammaproteobacteria family Vibrionaceae. This study follows the identification of WS coral pathogens from the initial isolation of putative pathogens, through the design and execution of infection experiments, to the final phylogenic classification of these deadly pathogens and the identification of their unique virulence mechanism. Readers with general interest in the field of coral diseases will find great benefit following the narrative of this study, while scientists specializing in the study of coral diseases will find in this detailed and comprehensive work a detailed manual to mastering the art of coral pathogen identification.