Dimensional scaling offers a new approach to quantum dynamical correlations. This is the first book dealing with dimensional scaling methods in the quantum theory of atoms and molecules. Appropriately, it is a multiauthor production, derived chiefly from papers presented at a workshop held in June 1991 at the Ørsted Institute in Copenhagen. Although focused on dimensional scaling, the volume includes contributions on other unorthodox methods for treating nonseparable dynamical problems and electronic correlation. In shaping the book, the editors serve three needs: an introductory tutorial for this still fledgling field; a guide to the literature; and an inventory of current research results and prospects. Part I treats basic aspects of dimensional scaling. Addressed to readers entirely unfamiliar with the subject, it provides both a qualitative overview, and a tour of elementary quantum mechanics. Part II surveys the research frontier. The eight chapters exemplify current techniques and outline results. Part III presents other methods, including nonseparable dynamics, and electron correlation in pseudomolecular excited states of atoms. Although procrustean conformity was not imposed, unifying and complementary themes are emphasized throughout the book.