This book covers broad aspects of the chemistry of π-stacked polymers and low-molecular-weight molecules, from synthesis through theory. It is intended for graduate students and researchers in academia and industry and consists of chapters written by renowned scientists who have made significant contributions to this field in the past decade. π-Stacked polymers and low-molecular-weight molecules are expected to replace main-chain conjugated polymers such as polyacetylenes and polythiophenes as organic conducting and energy-transferring substances that are important as materials for photo-electronic applications. π-Stacked polymers and molecules have significant advantages over main-chain conjugated polymers, i.e., high solubility in solvents, large freedom in molecular design, and colorless nature.