The Cladoniaceae are a family of lichen-forming fungi (Ascomycotine: Lecanorales, suborder Cladoniinae) that inlcudes more than 400 species. Cladoniaceae species are found on all continents, and many are conspicuous and easily recognized because of their conspicuous colors (e.g., scarlet or white). The commercial uses of Cladoniaceae largely occur outside the Neotropics and include the prinicipal winter food for wild or semidomesticated reindeer or caribou. They are also used for decoration in many parts of the world and as tree models in architectural projects. Some are sources of industrial antibacterial medicines. This volume treats the neotropical Cladoniaceae and recognizes 184 species in four genera. Twenty-nine taxa are described as new. Includes keys, descriptions, distribution maps, and photographic images.