This book is a compilation of calculated structural geometries and heats of formation of approximately 750 known saturated polycyclic hydrocarbons having from 5 to 15 carbon atoms and consisting of three to seven rings, i.e., CsHj (tricyclopentanes) to CjsHig (heptacyclopentadecanes). Molecular mechanics provides a facile way to calculate not only the heat of formation of a molecule but also the geometry of the corresponding structure. The International Union of Pure and Applied Chemistry (IUPAC) and the Chemical Abstracts names of the compounds, along with any trivial names that have been published in the literature, have been supplied. A number of polycyclic hydrocarbons, whose syntheses have not yet been reported in the chemical literature, have been the subject of theoretical interest. Although many of these provide exciting synthetic challenges to organic chemists, only those compounds whose syntheses have been reported are included here. Also, the compounds presented are those polycyclic hydrocarbons that do not possess substituents or bonds that are not part of a ring. Since the initial report of the synthesis of a given compound does not always provide the best synthetic method, and, in fact, later preparative schemes have often produced higher yields and more easily isolable products, literature references are not cited. Rather, the reader can obtain further information for each of the compounds and all references to any specific compound, including its synthesis, through the Chemical Abstracts Service registry numbers (CAS RNs). The methods used in the computation of structures, heats of formation, and nomenclature are discussed in subsequent sections. The compounds within each chapter are arranged by their IUPAC names.