This book classifies methods of synthesizing a heterocyclic ring which is fused to another ring. Classification is based on the functional group or groups present in the substrate, each chapter being devoted to the reactions of a particular pair of groups. The groups are arranged alphabetically so that they can be found easily. The book enables the reader to locate references (over 2000 are included) to the conversion of a wide variety of functional groups into heterocyclic rings of five to eight atoms. Each cyclization is shown as an equation which contains concise details or reagents, conditions, and yields. Since the classification of each cyclization is based on the functional groups involved, locating the relevant reference is independent of the identity of the ring in the substrate. This simplifies the search for the relevant reference.