Research into an organism’s microbiome has become exceedingly popular over the past two decades. These studies have highlighted corals as an excellent model group and illustrated the importance of the host-microbiome relationship within the coral holobiont. Symbioses within the holobiont include a spectrum of relationships ranging from beneficial to harmful. Indeed, the hunt for coral pathogens when a coral bleaches or succumbs to disease is widely researched but comes with its fair share of controversy. In this chapter, we attempt to un-pick the facts from fiction and present a synopsis of the current knowledge on bleaching, disease, dysbiosis, and the role of the microbiome in all this.