Crayfishes, also known as crawfish, crawdads, or mudbugs, are a diverse and important component of freshwater aquatic and semi-aquatic ecosystems around the world. Their familiar form is recognizable by almost anyone who has spent time in and around lakes or creeks. Crayfishes are found natively on every continent except Africa and Antarctica and occur in almost every type of aquatic and semi-aquatic habitat. This book intends to provide an up-to-date list of known crayfish species from the state of Kentucky. Distribution maps, illustrations, photos, and a key are provided to assist those interested in identifying Kentucky crayfishes. Information on the habitat and biology of each species is also provided, as is a summary of the historical efforts of crayfish biologists, or astacologists, in the state.