This book gives a detailed description of Gedeo derivational morphology. Gedeo, one of the little studied languages in Ethiopia, is categorized under Highland East Cushitic (HEC) sub-family. The topics covered in the book include Suffixation, Compounding, and Reduplication that are found to be productive in the language along with the some background information about Gedeo people and culture. It is useful for anyone who wants to refer to the morphology of the language, and make further study on it. The book develops different word formation rules of Gedeo based on the lexicalist''s assumption that "words with derivational morphology and compound words cannot be derived through syntactic transformation as they should be part of the lexicon." Thus, different word formation rules are applied on the major word classes to derive new lexemes by feature percolation.